Unilateral adaptation of the human angular vestibulo-ocular reflex.
Migliaccio, Americo A; Schubert, Michael C
2013-02-01
A recent study showed that the angular vestibulo-ocular reflex (VOR) can be better adaptively increased using an incremental retinal image velocity error signal compared with a conventional constant large velocity-gain demand (×2). This finding has important implications for vestibular rehabilitation that seeks to improve the VOR response after injury. However, a large portion of vestibular patients have unilateral vestibular hypofunction, and training that raises their VOR response during rotations to both the ipsilesional and contralesional side is not usually ideal. We sought to determine if the vestibular response to one side could selectively be increased without affecting the contralateral response. We tested nine subjects with normal vestibular function. Using the scleral search coil and head impulse techniques, we measured the active and passive VOR gain (eye velocity / head velocity) before and after unilateral incremental VOR adaptation training, consisting of self-generated (active) head impulses, which lasted ≈ 15 min. The head impulses consisted of rapid, horizontal head rotations with peak-amplitude 15°, peak-velocity 150°/s and peak-acceleration 3,000°/s(2). The VOR gain towards the adapting side increased after training from 0.92 ± 0.18 to 1.11 ± 0.22 (+22.7 ± 20.2 %) during active head impulses and from 0.91 ± 0.15 to 1.01 ± 0.17 (+11.3 ± 7.5 %) during passive head impulses. During active impulses, the VOR gain towards the non-adapting side also increased by ≈ 8 %, though this increase was ≈ 70 % less than to the adapting side. A similar increase did not occur during passive impulses. This study shows that unilateral vestibular adaptation is possible in humans with a normal VOR; unilateral incremental VOR adaptation may have a role in vestibular rehabilitation. The increase in passive VOR gain after active head impulse adaptation suggests that the training effect is robust.
Adaptive Neural Network Controller for Thermogenerator Angular Velocity Stabilization System
2013-01-01
The paper presents an analytical and simulation approach for the selection of activation functions for the class of neural network controllers for ship’s thermogenerator angular velocity stabilization system. Such systems can be found in many ships. A Lyapunov-like stability analysis is performed in order to obtain a weight update law. A number of simulations were performed to find the best activation function using integral error criteria and statistical T-tests.
Spatio-angular Minimum-variance Tomographic Controller for Multi-Object Adaptive Optics systems
Correia, Carlos M; Veran, Jean-Pierre; Andersen, David; Lardiere, Olivier; Bradley, Colin
2015-01-01
Multi-object astronomical adaptive-optics (MOAO) is now a mature wide-field observation mode to enlarge the adaptive-optics-corrected field in a few specific locations over tens of arc-minutes. The work-scope provided by open-loop tomography and pupil conjugation is amenable to a spatio-angular Linear-Quadratic Gaussian (SA-LQG) formulation aiming to provide enhanced correction across the field with improved performance over static reconstruction methods and less stringent computational complexity scaling laws. Starting from our previous work [1], we use stochastic time-progression models coupled to approximate sparse measurement operators to outline a suitable SA-LQG formulation capable of delivering near optimal correction. Under the spatio-angular framework the wave-fronts are never explicitly estimated in the volume,providing considerable computational savings on 10m-class telescopes and beyond. We find that for Raven, a 10m-class MOAO system with two science channels, the SA-LQG improves the limiting mag...
Yakushin, Sergei B
2012-06-01
The gain of the vertical angular vestibulo-ocular reflex (aVOR) was adaptively increased and decreased in a side-down head orientation for 4 h in two cynomolgus monkeys. Adaptation was performed at 0.25, 1, 2, or 4 Hz. The gravity-dependent and -independent gain changes were determined over a range of head orientations from left-side-down to right-side-down at frequencies from 0.25 to 10 Hz, before and after adaptation. Gain changes vs. frequency data were fit with a Gaussian to determine the frequency at which the peak gain change occurred, as well as the tuning width. The frequency at which the peak gravity-dependent gain change occurred was approximately equal to the frequency of adaptation, and the width increased monotonically with increases in the frequency of adaptation. The gravity-independent component was tuned to the adaptive frequency of 0.25 Hz but was uniformly distributed over all frequencies when the adaptation frequency was 1-4 Hz. The amplitude of the gravity-independent gain changes was larger after the aVOR gain decrease than after the gain increase across all tested frequencies. For the aVOR gain decrease, the phase lagged about 4° for frequencies below the adaptation frequency and led for frequencies above the adaptation frequency. For gain increases, the phase relationship as a function of frequency was inverted. This study demonstrates that the previously described dependence of aVOR gain adaptation on frequency is a property of the gravity-dependent component of the aVOR only. The gravity-independent component of the aVOR had a substantial tuning curve only at an adaptation frequency of 0.25 Hz.
Adaptive non-collinear autocorrelation of few-cycle pulses with an angular tunable bi-mirror
Energy Technology Data Exchange (ETDEWEB)
Treffer, A., E-mail: treffer@mbi-berlin.de; Bock, M.; König, S.; Grunwald, R. [Max Born Institute for Nonlinear Optics and Short-Pulse Spectroscopy, Max Born Strasse 2A, D-12489 Berlin (Germany); Brunne, J.; Wallrabe, U. [Laboratory for Microactuators, Department of Microsystems Engineering, IMTEK, University of Freiburg, Georges-Koehler-Allee 102, Freiburg 79110 (Germany)
2016-02-01
Adaptive autocorrelation with an angular tunable micro-electro-mechanical system is reported. A piezo-actuated Fresnel bi-mirror structure was applied to measure the second order autocorrelation of near-infrared few-cycle laser pulses in a non-collinear setup at tunable superposition angles. Because of enabling measurements with variable scaling and minimizing the influence of distortions by adaptive self-reconstruction, the approach extends the capability of autocorrelators. Flexible scaling and robustness against localized amplitude obscurations are demonstrated. The adaptive reconstruction of temporal frequency information by the Fourier analysis of autocorrelation data is shown. Experimental results and numerical simulations of the beam propagation and interference are compared for variable angles.
Pan, M.-Ch.; Chu, W.-Ch.; Le, Duc-Do
2016-12-01
The paper presents an alternative Vold-Kalman filter order tracking (VKF_OT) method, i.e. adaptive angular-velocity VKF_OT technique, to extract and characterize order components in an adaptive manner for the condition monitoring and fault diagnosis of rotary machinery. The order/spectral waveforms to be tracked can be recursively solved by using Kalman filter based on the one-step state prediction. The paper comprises theoretical derivation of computation scheme, numerical implementation, and parameter investigation. Comparisons of the adaptive VKF_OT scheme with two other ones are performed through processing synthetic signals of designated order components. Processing parameters such as the weighting factor and the correlation matrix of process noise, and data conditions like the sampling frequency, which influence tracking behavior, are explored. The merits such as adaptive processing nature and computation efficiency brought by the proposed scheme are addressed although the computation was performed in off-line conditions. The proposed scheme can simultaneously extract multiple spectral components, and effectively decouple close and crossing orders associated with multi-axial reference rotating speeds.
Wei, Zhao; Tao, Feng; Jun, Wang
2013-10-01
An efficient, robust, and accurate approach is developed for image registration, which is especially suitable for large-scale change and arbitrary rotation. It is named the adequately sampling polar transform and weighted angular projection function (ASPT-WAPF). The proposed ASPT model overcomes the oversampling problem of conventional log-polar transform. Additionally, the WAPF presented as the feature descriptor is robust to the alteration in the fovea area of an image, and reduces the computational cost of the following registration process. The experimental results show two major advantages of the proposed method. First, it can register images with high accuracy even when the scale factor is up to 10 and the rotation angle is arbitrary. However, the maximum scaling estimated by the state-of-the-art algorithms is 6. Second, our algorithm is more robust to the size of the sampling region while not decreasing the accuracy of the registration.
Penland, Cecile; Ghil, Michael; Weickmann, Klaus M.
1991-01-01
The spectral resolution and statistical significance of a harmonic analysis obtained by low-order MEM can be improved by subjecting the data to an adaptive filter. This adaptive filter consists of projecting the data onto the leading temporal empirical orthogonal functions obtained from singular spectrum analysis (SSA). The combined SSA-MEM method is applied both to a synthetic time series and a time series of AAM data. The procedure is very effective when the background noise is white and less so when the background noise is red. The latter case obtains in the AAM data. Nevertheless, reliable evidence for intraseasonal and interannual oscillations in AAM is detected. The interannual periods include a quasi-biennial one and an LF one, of 5 years, both related to the El Nino/Southern Oscillation. In the intraseasonal band, separate oscillations of about 48.5 and 51 days are ascertained.
Shakur, Asif; Sinatra, Taylor
2013-01-01
The gyroscope in a smartphone was employed in a physics laboratory setting to verify the conservation of angular momentum and the nonconservation of rotational kinetic energy. As is well-known, smartphones are ubiquitous on college campuses. These devices have a panoply of built-in sensors. This creates a unique opportunity for a new paradigm in…
Metwalli, Nader S; Hu, Xiaoping P; Carew, John D
2010-09-01
Q-ball imaging (QBI) is a high angular resolution diffusion-weighted imaging (HARDI) technique for reconstructing the orientation distribution function (ODF). Some form of smoothing or regularization is typically required in the ODF reconstruction from low signal-to-noise ratio HARDI data. The amount of smoothing or regularization is usually set a priori at the discretion of the investigator. In this article, we apply an adaptive and objective means of smoothing the raw HARDI data using the smoothing splines on the sphere method with generalized cross-validation (GCV) to estimate the diffusivity profile in each voxel. Subsequently, we reconstruct the ODF, from the smoothed data, based on the Funk-Radon transform (FRT) used in QBI. The spline method was applied to both simulated data and in vivo human brain data. Simulated data show that the smoothing splines on the sphere method with GCV smoothing reduces the mean squared error in estimates of the ODF as compared with the standard analytical QBI approach. The human data demonstrate the utility of the method for estimating smooth ODFs.
Shternin, Peter S; Vasyutinskii, Oleg S
2008-05-21
We present a theoretical framework for calculating the recoil-angle dependence of the photofragment angular momentum polarization taking into account both radial and Coriolis nonadiabatic interactions in the diatomic/linear photodissociating molecules. The parity-adapted representation of the total molecular wave function has been used throughout the paper. The obtained full quantum-mechanical expressions for the photofragment state multipoles have been simplified by using the semiclassical approximation in the high-J limit and then analyzed for the cases of direct photodissociation and slow predissociation in terms of the anisotropy parameters. In both cases, each anisotropy parameter can be presented as a linear combination of the generalized dynamical functions fK(q,q',q,q') of the rank K representing contribution from different dissociation mechanisms including possible radial and Coriolis nonadiabatic transitions, coherent effects, and the rotation of the recoil axis. In the absence of the Coriolis interactions, the obtained results are equivalent to the earlier published ones. The angle-recoil dependence of the photofragment state multipoles for an arbitrary photolysis reaction is derived. As shown, the polarization of the photofragments in the photolysis of a diatomic or a polyatomic molecule can be described in terms of the anisotropy parameters irrespective of the photodissociation mechanism.
Karpov, Valeri
2015-01-01
A comprehensive guide to AngularJS, Google's open-source client-side framework for app development. Most of the existing guides to AngularJS struggle to provide simple and understandable explanations for more advanced concepts. As a result, some developers who understand all the basic concepts of AngularJS struggle when it comes to building more complex real-world applications. Professional AngularJS provides a thorough understanding of AngularJS, covering everything from basic concepts, such as directives and data binding, to more advanced concepts like transclusion, build systems, and auto
Sweet, Sarah M.; Sharp, Robert; Glazebrook, Karl; Rigaut, Francois; Carrasco, Eleazar R.; Brodwin, Mark; Bayliss, Matthew; Stalder, Brian; Abraham, Roberto; McGregor, Peter
2017-01-01
We present the stellar mass-size relation for 49 galaxies within the z = 1.067 cluster SPT-CL J0546-5345, with full width at half-maximum ˜80-120 mas Ks-band data from the Gemini multiconjugate adaptive optics system (GeMS/GSAOI). This is the first such measurement in a cluster environment, performed at sub-kpc resolution at rest-frame wavelengths dominated by the light of the underlying old stellar populations. The observed stellar mass-size relation is offset from the local relation by 0.21 dex, corresponding to a size evolution proportional to (1 + z)-1.25, consistent with the literature. The slope of the stellar mass-size relation β = 0.74 ± 0.06, consistent with the local relation. The absence of slope evolution indicates that the amount of size growth is constant with stellar mass. This suggests that galaxies in massive clusters such as SPT-CL J0546-5345 grow via processes that increase the size without significant morphological interference, such as minor mergers and/or adiabatic expansion. The slope of the cluster stellar mass-size relation is significantly shallower if measured in Hubble Space Telescope (HST)/Advanced Camera for Surveys imaging at wavelengths blueward of the Balmer break, similar to rest-frame ultraviolet relations at z = 1 in the literature. The stellar mass-size relation must be measured at redder wavelengths, which are more sensitive to the old stellar population that dominates the stellar mass of the galaxies. The slope is unchanged when GeMS Ks-band imaging is degraded to the resolution of K-band HST/Near Infrared Camera and Multi-Object Spectrometer resolution but dramatically affected when degraded to Ks-band Magellan/FourStar resolution. Such measurements must be made with adaptive optics in order to accurately characterize the sizes of compact, z = 1 galaxies.
Schwinger, J.
1952-01-26
The commutation relations of an arbitrary angular momentum vector can be reduced to those of the harmonic oscillator. This provides a powerful method for constructing and developing the properties of angular momentum eigenvectors. In this paper many known theorems are derived in this way, and some new results obtained. Among the topics treated are the properties of the rotation matrices; the addition of two, three, and four angular momenta; and the theory of tensor operators.
Sweet, Sarah M; Glazebrook, Karl; Rigaut, Francois; Carrasco, Eleazar R; Brodwin, Mark; Baylliss, Matthew; Stalder, Brian; Abraham, Roberto; McGregor, Peter
2016-01-01
We present the stellar mass - size relation for 49 galaxies within the $z$ = 1.067 cluster SPT-CL J0546$-$5345, with FWHM $\\sim$80-120 mas $K_{\\mathrm s}$-band data from the Gemini multi-conjugate adaptive optics system (GeMS/GSAOI). This is the first such measurement in a cluster environment, performed at sub-kpc resolution at rest-frame wavelengths dominated by the light of the underlying old stellar populations. The observed stellar mass - size relation is offset from the local relation by 0.21 dex, corresponding to a size evolution proportional to $(1+z)^{-1.25}$, consistent with the literature. The slope of the stellar mass - size relation $\\beta$ = 0.74 $\\pm$ 0.06, consistent with the local relation. The absence of slope evolution indicates that the amount of size growth is constant with stellar mass. This suggests that galaxies in massive clusters such as SPT-CL J0546$-$5345 grow via processes that increase the size without significant morphological interference, such as minor mergers and/or adiabatic ...
Quark Orbital Angular Momentum
Directory of Open Access Journals (Sweden)
Burkardt Matthias
2015-01-01
Full Text Available Definitions of orbital angular momentum based on Wigner distributions are used as a framework to discuss the connection between the Ji definition of the quark orbital angular momentum and that of Jaffe and Manohar. We find that the difference between these two definitions can be interpreted as the change in the quark orbital angular momentum as it leaves the target in a DIS experiment. The mechanism responsible for that change is similar to the mechanism that causes transverse single-spin asymmetries in semi-inclusive deep-inelastic scattering.
Recurrence of angular cheilitis.
Ohman, S C; Jontell, M; Dahlen, G
1988-08-01
The incidence of recurrence of angular cheilitis following a successful antimicrobial treatment was studied in 48 patients. Clinical assessments including a microbial examination were carried out 8 months and 5 yr after termination of treatment. Eighty percent of the patients reported recurrence of their angular cheilitis on one or more occasions during the observation period. Patients with cutaneous disorders associated with dry skin or intraoral leukoplakia had an increased incidence of recrudescence. Neither the presence of denture stomatitis nor the type of microorganisms isolated from the original lesions of angular cheilitis, i.e. Candida albicans and/or Staphylococcus aureus, were associated with the number of recurrences. The present observations indicate that treatment of the majority of patients with angular cheilitis should be considered in a longer perspective than previously supposed, due to the short lasting therapeutic effects of the antimicrobial therapy.
[Malignant angular cheilitis].
Seoane, J; Vázquez, J; Cazenave, A; de la Cruz Mera, A; Argila, F; Aguado, A
1996-01-01
A case of chronic angular cheilitis is reported. Candida albicans was isolated repeatedly and the process developed into epitheliomatous carcinoma. The etiopathogenic role of Candida albicans and possible mechanism of action are discussed.
Gema Nazriyanti
2008-01-01
Angular cheilitis adalah inflamasi akut atau kronis pada sudut mulut yang ditandai dengan adanya flsur-fisur, retak-retak pada sudut bibir, berwarna kemerahan, mengalami ulserasi disertai rasa terbakar, nyeri dan rasa kering pada sudut mulut. Dapat mengenai orang tua, dewasa dan anak-anak. Banyak pendapat yang mengemukakan tentang etiologi dari angular cheilitis, antara lain defisiensi vitamin B kompleks, denture soremouth, defisiensi besi, kebiasaan bernafas melalui mulut, membasahi bib...
Optical orbital angular momentum
Barnett, Stephen M.; Babiker, Mohamed; Padgett, Miles J.
2017-01-01
We present a brief introduction to the orbital angular momentum of light, the subject of our theme issue and, in particular, to the developments in the 13 years following the founding paper by Allen et al. (Allen et al. 1992 Phys. Rev. A 45, 8185 (doi:10.1103/PhysRevA.45.8185)). The papers by our invited authors serve to bring the field up to date and suggest where developments may take us next. This article is part of the themed issue ‘Optical orbital angular momentum’. PMID:28069775
Optical orbital angular momentum
Barnett, Stephen M.; Babiker, Mohamed; Padgett, Miles J.
2017-02-01
We present a brief introduction to the orbital angular momentum of light, the subject of our theme issue and, in particular, to the developments in the 13 years following the founding paper by Allen et al. (Allen et al. 1992 Phys. Rev. A 45, 8185 (doi:10.1103/PhysRevA.45.8185)). The papers by our invited authors serve to bring the field up to date and suggest where developments may take us next. This article is part of the themed issue 'Optical orbital angular momentum'.
Parker, G. W.
1978-01-01
Discusses, classically and quantum mechanically, the angular momentum induced in the bound motion of an electron by an external magnetic field. Calculates the current density and its magnetic moment, and then uses two methods to solve the first-order perturbation theory equation for the required eigenfunction. (Author/GA)
"Angular" plasma cell cheilitis.
da Cunha Filho, Roberto Rheingantz; Tochetto, Lucas Baldissera; Tochetto, Bruno Baldissera; de Almeida, Hiram Larangeira; Lorencette, Nádia Aparecida; Netto, José Fillus
2014-03-17
Plasma cell cheilitis is an extremely rare disease, characterized by erythematous-violaceous, ulcerated and asymptomatic plaques, which evolve slowly. The histological characteristics include dermal infiltrate composed of mature plasmocytes. We report a case of Plasma cell angular cheilitis in a 58-year-old male, localized in the lateral oral commissure.
"Angular" plasma cell cheilitis
da Cunha Filho, Roberto Rheingantz; Tochetto, Lucas Baldissera; Tochetto, Bruno Baldissera; de Almeida Jr, Hiram Larangeira; Lorencette, Nadia Aparecida; Netto, Jose Fillus
2014-01-01
Plasma cell cheilitis is an extremely rare disease, characterized by erythematous-violaceous, ulcerated and asymptomatic plaques, which evolve slowly. The histological characteristics include dermal infiltrate composed of mature plasmocytes. We report a case of Plasma cell angular cheilitis in a 58-year-old male, localized in the lateral oral commissure.
Institute of Scientific and Technical Information of China (English)
蚩军祥; 赵辉; 翁兴伟; 轩永波
2012-01-01
Aiming at the problem that air-to-ground weapons attack precisely, a terminal guidance law of the self-adaption variable structure with sliding mode considering angular constraint was deduced. Based on the self-adaption variable structure, the angular constraint was introduced,so that the guidance law could meet the demands of both guidance precision and impact angle. The simulation result shows that the guidance law not only has good guidance precision when attacking moving target on the ground, but also can fit the angular constraint. The result is instructive for combat operation of air-to-ground precision guided weapons.%针对空对地攻击武器对地面目标的精确打击问题,提出了一种带落角约束的自适应滑模变结构末制导律.该制导律在自适应滑模导引律的基础上,引入落角约束项,可以满足制导精度和落角的双重要求.仿真结果表明,该制导律对地面活动目标的攻击既具有较高的制导精度,又可以满足落角要求,对空地精确制导武器的作战使用具有指导意义.
Angular cheilitis after tonsillectomy.
England, R J; Lau, M; Ell, S R
1999-08-01
The operation of tonsillectomy requires the oral cavity to be held open mechanically in an unconscious patient, and intra-oral instrumentation to occur. Angular cheilitis may arise as a result of this after operation. This can cause morbidity and delay the re-establishment of a normal diet. The aim of this study was to identify what factors increase the likelihood of developing this problem postoperatively. Sixty patients were randomly selected in a prospective manner. Preoperative, intraoperative and postoperative variables were recorded. The frequency of development of postoperative angular cheilitis was recorded. The prevalence of the condition was related to the prerecorded variables. Parametric analysis showed that the chance of developing angular cheilitis was directly related to the use of diathermy haemostasis (P = 0.05). Logistic regression analysis showed that the odds ratio of developing this complication if diathermy was used is 3.5 (95% confidence intervals 0.99, 12.4) and operation difficulty may also be a relevant variable. No other recorded variables were found to be significant.
Quantum Heuristics of Angular Momentum
Levy-Leblond, Jean-Marc
1976-01-01
Discusses the quantization of angular momentum components, Heisenberg-type inequalities for their spectral dispersions, and the quantization of the angular momentum modulus, without using operators or commutation relations. (MLH)
Vanston, Alex
2013-01-01
This book uses a practical, step-by-step approach, starting with how to build directives from the ground up before moving on to creating web applications comprised of multiple modules all working together to provide the best user experience possible.This book is intended for intermediate JavaScript developers who are looking to enhance their understanding of single-page web application development with a focus on AngularJS and the JavaScript MVC frameworks.It is expected that readers will understand basic JavaScript patterns and idioms and can recognize JSON formatted data.
Orbital angular momentum microlaser
Miao, Pei; Zhang, Zhifeng; Sun, Jingbo; Walasik, Wiktor; Longhi, Stefano; Litchinitser, Natalia M.; Feng, Liang
2016-07-01
Structured light provides an additional degree of freedom for modern optics and practical applications. The effective generation of orbital angular momentum (OAM) lasing, especially at a micro- and nanoscale, could address the growing demand for information capacity. By exploiting the emerging non-Hermitian photonics design at an exceptional point, we demonstrate a microring laser producing a single-mode OAM vortex lasing with the ability to precisely define the topological charge of the OAM mode. The polarization associated with OAM lasing can be further manipulated on demand, creating a radially polarized vortex emission. Our OAM microlaser could find applications in the next generation of integrated optoelectronic devices for optical communications in both quantum and classical regimes.
Angular integrals in d dimensions
Energy Technology Data Exchange (ETDEWEB)
Somogyi, Gabor
2011-01-15
We discuss the evaluation of certain d dimensional angular integrals which arise in perturbative field theory calculations. We find that the angular integral with n denominators can be computed in terms of a certain special function, the so-called H-function of several variables. We also present several illustrative examples of the general result and briefly consider some applications. (orig.)
Intrinsic Angular Momentum of Light.
Santarelli, Vincent
1979-01-01
Derives a familiar torque-angular momentum theorem for the electromagnetic field, and includes the intrinsic torques exerted by the fields on the polarized medium. This inclusion leads to the expressions for the intrinsic angular momentum carried by the radiation traveling through a charge-free medium. (Author/MA)
Angular momentum of sound pulses.
Lekner, John
2006-07-05
Three-dimensionally localized acoustic pulses in an isotropic fluid medium necessarily have transverse components of momentum density. Those with an azimuthal component of momentum density can carry angular momentum. The component of total pulse angular momentum along the direction of the total momentum is an invariant (constant in time and independent of choice of origin). The pulse energy, momentum and angular momentum are evaluated analytically for a family of localized solutions of the wave equation. In the limit where the pulses have many oscillations within their spatial extent ([Formula: see text], where k is the wavenumber and a determines the size of a pulse), the energy, momentum and angular momentum are consistent with a multiphonon representation of the pulse, each phonon having energy [Formula: see text], momentum [Formula: see text] and angular momentum [Formula: see text] (with integer m).
Orbital angular momentum in optical waves propagating through distributed turbulence.
Sanchez, Darryl J; Oesch, Denis W
2011-11-21
This is the second of two papers demonstrating that photons with orbital angular momentum can be created in optical waves propagating through distributed turbulence. In the companion paper, it is shown that propagation through atmospheric turbulence can create non-trivial angular momentum. Here, we extend the result and demonstrate that this momentum is, at least in part, orbital angular momentum. Specifically, we demonstrate that branch points (in the language of the adaptive optic community) indicate the presence of photons with non-zero OAM. Furthermore, the conditions required to create photons with non-zero orbital angular momentum are ubiquitous. The repercussions of this statement are wide ranging and these are cursorily enumerated.
Bailey, Simon
2015-01-01
This book is intended for developers who have an understanding of the basic principles behind both AngularJS and test-driven development. You, as a developer, are interested in eliminating the fear related to either introducing tests to an existing codebase or starting out testing on a fresh AngularJS application. If you're a team leader or part of a QA team with the responsibility of ensuring full test coverage of an application, then this book is ideal for you to comprehend the full testing scope required by your developers. Whether you're new to or are well versed with AngularJS, this book
Angular anisoplanatism of a focused beam using beacons over horizontal path
Wu, Wu-ming; Ning, Yu
2016-01-01
The performance of the achieve laser beam propagation through atmospheric turbulence with adaptive optics is degraded by the fact that the wavefront aberrations difference. This error is only include the angular anisoplanatism when there is separation between the achieve laser beam and beacon. In the paper we derive an analytic expression for the effective angular anisoplanatism as a function of displacement angular when the turbulence profile is uniform. It shows that the effective angular anisoplanatism becomes weaker as the diameter of laser beams and the Fried transverse coherence length increase. We report results from field experiments that the effective angular anisoplanatism of a focused beam over horizontal path. It is found that measured and theoretical results are consistent. The effective wavefront variance increases with the strength of atmospheric turbulence and the angular displacement. And the constant phase of angular anisoplanatism has no effect on the Strehl ratio of the beam.
Menard, Dan
2013-01-01
Get to grips with a new technology, understand what it is and what it can do for you, and then get to work with the most important features and tasks. This book is written in an easytoread style, with a strong emphasis on realworld, practical examples. Stepbystep explanations are provided for performing important tasks.This book is for web developers familiar with JavascriptIt doesn't cover the history of AngularJS, and it's not a pitch to convince you that AngularJS is the best framework on the entire web. It's a guide to help you learn everything you need to know about AngularJS in as few pa
Angular momentum in human walking.
Herr, Hugh; Popovic, Marko
2008-02-01
Angular momentum is a conserved physical quantity for isolated systems where no external moments act about a body's center of mass (CM). However, in the case of legged locomotion, where the body interacts with the environment (ground reaction forces), there is no a priori reason for this relationship to hold. A key hypothesis in this paper is that angular momentum is highly regulated throughout the walking cycle about all three spatial directions [|Lt| approximately 0], and therefore horizontal ground reaction forces and the center of pressure trajectory can be explained predominantly through an analysis that assumes zero net moment about the body's CM. Using a 16-segment human model and gait data for 10 study participants, we found that calculated zero-moment forces closely match experimental values (Rx2=0.91; Ry2=0.90). Additionally, the centroidal moment pivot (point where a line parallel to the ground reaction force, passing through the CM, intersects the ground) never leaves the ground support base, highlighting how closely the body regulates angular momentum. Principal component analysis was used to examine segmental contributions to whole-body angular momentum. We found that whole-body angular momentum is small, despite substantial segmental momenta, indicating large segment-to-segment cancellations ( approximately 95% medio-lateral, approximately 70% anterior-posterior and approximately 80% vertical). Specifically, we show that adjacent leg-segment momenta are balanced in the medio-lateral direction (left foot momentum cancels right foot momentum, etc.). Further, pelvis and abdomen momenta are balanced by leg, chest and head momenta in the anterior-posterior direction, and leg momentum is balanced by upper-body momentum in the vertical direction. Finally, we discuss the determinants of gait in the context of these segment-to-segment cancellations of angular momentum.
Non-Colinearity of Angular Velocity and Angular Momentum
Burr, A. F.
1974-01-01
Discusses the principles, construction, and operation of an apparatus which serves to demonstrate the non-colinearity of the angular velocity and momentum vectors as well as the inertial tensors. Applications of the apparatus to teaching of advanced undergraduate mechanics courses are recommended. (CC)
Olympic Wrestling and Angular Momentum.
Carle, Mark
1988-01-01
Reported is the use of a wrestling photograph in a noncalculus introductory physics course. The photograph presents a maneuver that could serve as an example for a discussion on equilibrium, forces, torque, and angular motion. Provided are some qualitative thoughts as well as quantitative calculations. (YP)
The angular momentum of baryons and dark matter halos revisited
Kimm, Taysun; Slyz, Adrianne; Pichon, Christophe; Kassin, Susan A; Dubois, Yohan
2011-01-01
Recent theoretical studies have shown that galaxies at high redshift are fed by cold, dense gas filaments, suggesting angular momentum transport by gas differs from that by dark matter. Revisiting this issue using high-resolution cosmological hydrodynamics simulations with adaptive mesh refinement, we find that at the time of accretion, gas and dark matter do carry a similar amount of specific angular momentum, but that it is systematically higher than that of the dark matter halo as a whole. At high redshift, freshly accreted gas rapidly streams into the central region of the halo, directly depositing this large amount of angular momentum within a sphere of radius r=0.1rvir. In contrast, dark matter particles pass through the central region unscathed, and a fraction of them ends up populating the outer regions of the halo (r/rvir>0.1), redistributing angular momentum in the process. As a result, large-scale motions of the cosmic web have to be considered as the origin of gas angular momentum rather than its ...
The Angular Momentum of Baryons and Dark Matter Halos Revisited
Kimm, Taysun; Devriendt, Julien; Slyz, Adrianne; Pichon, Christophe; Kassin, Susan A.; Dubois, Yohan
2011-01-01
Recent theoretical studies have shown that galaxies at high redshift are fed by cold, dense gas filaments, suggesting angular momentum transport by gas differs from that by dark matter. Revisiting this issue using high-resolution cosmological hydrodynamics simulations with adaptive-mesh refinement (AMR), we find that at the time of accretion, gas and dark matter do carry a similar amount of specific angular momentum, but that it is systematically higher than that of the dark matter halo as a whole. At high redshift, freshly accreted gas rapidly streams into the central region of the halo, directly depositing this large amount of angular momentum within a sphere of radius r = 0.1R(sub vir). In contrast, dark matter particles pass through the central region unscathed, and a fraction of them ends up populating the outer regions of the halo (r/R(sub vir) > 0.1), redistributing angular momentum in the process. As a result, large-scale motions of the cosmic web have to be considered as the origin of gas angular momentum rather than its virialised dark matter halo host. This generic result holds for halos of all masses at all redshifts, as radiative cooling ensures that a significant fraction of baryons remain trapped at the centre of the halos. Despite this injection of angular momentum enriched gas, we predict an amount for stellar discs which is in fair agreement with observations at z=0. This arises because the total specific angular momentum of the baryons (gas and stars) remains close to that of dark matter halos. Indeed, our simulations indicate that any differential loss of angular momentum amplitude between the two components is minor even though dark matter halos continuously lose between half and two-thirds of their specific angular momentum modulus as they evolve. In light of our results, a substantial revision of the standard theory of disc formation seems to be required. We propose a new scenario where gas efficiently carries the angular momentum generated
Plate tectonics conserves angular momentum
Directory of Open Access Journals (Sweden)
C. Bowin
2009-03-01
Full Text Available A new combined understanding of plate tectonics, Earth internal structure, and the role of impulse in deformation of the Earth's crust is presented. Plate accelerations and decelerations have been revealed by iterative filtering of the quaternion history for the Euler poles that define absolute plate motion history for the past 68 million years, and provide an unprecedented precision for plate angular rotation variations with time at 2-million year intervals. Stage poles represent the angular rotation of a plate's motion between adjacent Euler poles, and from which the maximum velocity vector for a plate can be determined. The consistent maximum velocity variations, in turn, yield consistent estimates of plate accelerations and decelerations. The fact that the Pacific plate was shown to accelerate and decelerate, implied that conservation of plate tectonic angular momentum must be globally conserved, and that is confirmed by the results shown here (total angular momentum ~1.4 E+27 kgm^{2}s^{−1}. Accordingly, if a plate decelerates, other plates must increase their angular momentums to compensate. In addition, the azimuth of the maximum velocity vectors yields clues as to why the "bend" in the Emperor-Hawaiian seamount trend occurred near 46 Myr. This report summarizes processing results for 12 of the 14 major tectonic plates of the Earth (except for the Juan de Fuca and Philippine plates. Plate accelerations support the contention that plate tectonics is a product of torques that most likely are sustained by the sinking of positive density anomalies due to phase changes in subducted gabbroic lithosphere at depth in the upper lower mantle (above 1200 km depth. The tectonic plates are pulled along by the sinking of these positive mass anomalies, rather than moving at near constant velocity on the crests of convection cells driven by rising heat. These results imply that spreading centers are primarily passive reactive
Phonons with orbital angular momentum
Energy Technology Data Exchange (ETDEWEB)
Ayub, M. K. [Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); National Centre for Physics, Shahdra Valley Road, Quaid-i-Azam University Campus, Islamabad 44000 (Pakistan); Ali, S. [National Centre for Physics, Shahdra Valley Road, Quaid-i-Azam University Campus, Islamabad 44000 (Pakistan); Mendonca, J. T. [IPFN, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)
2011-10-15
Ion accoustic waves or phonon modes are studied with orbital angular momentum (OAM) in an unmagnetized collissionless uniform plasma, whose constituents are the Boltzmann electrons and inertial ions. For this purpose, we have employed the fluid equations to obtain a paraxial equation in terms of ion density perturbations and discussed its Gaussian beam and Laguerre-Gauss (LG) beam solutions. Furthermore, an approximate solution for the electrostatic potential problem is presented, allowing to express the components of the electric field in terms of LG potential perturbations. The energy flux due to phonons is also calculated and the corresponding OAM is derived. Numerically, it is shown that the parameters such as azimuthal angle, radial and angular mode numbers, and beam waist, strongly modify the profiles of the phonon LG potential. The present results should be helpful in understanding the phonon mode excitations produced by Brillouin backscattering of laser beams in a uniform plasma.
Angular momentum in QGP holography
Directory of Open Access Journals (Sweden)
Brett McInnes
2014-10-01
Full Text Available The quark chemical potential is one of the fundamental parameters describing the quark–gluon plasma produced by sufficiently energetic heavy-ion collisions. It is not large at the extremely high temperatures probed by the LHC, but it plays a key role in discussions of the beam energy scan programmes at the RHIC and other facilities. On the other hand, collisions at such energies typically (that is, in peripheral collisions give rise to very high values of the angular momentum density. Here we explain that holographic estimates of the quark chemical potential of a rotating sample of plasma can be very considerably improved by taking the angular momentum into account.
The integration of angular velocity
Boyle, Michael
2016-01-01
A common problem in physics and engineering is determination of the orientation of an object given its angular velocity. When the direction of the angular velocity changes in time, this is a nontrivial problem involving coupled differential equations. Several possible approaches are examined, along with various improvements over previous efforts. These are then evaluated numerically by comparison to a complicated but analytically known rotation that is motivated by the important astrophysical problem of precessing black-hole binaries. It is shown that a straightforward solution directly using quaternions is most efficient and accurate, and that the norm of the quaternion is irrelevant. Integration of the generator of the rotation can also be made roughly as efficient as integration of the rotation. Both methods will typically be twice as efficient naive vector- or matrix-based methods. Implementation by means of standard general-purpose numerical integrators is stable and efficient, so that such problems can ...
AngularJS test-driven development
Chaplin, Tim
2015-01-01
This book is for developers who want to learn about AngularJS development by applying testing techniques. You are assumed to have a basic knowledge and understanding of HTML, JavaScript, and AngularJS.
Optical angular momentum in dispersive media
Philbin, T G
2012-01-01
The angular momentum density and flux of light in a dispersive, rotationally symmetric medium are derived from Noether's theorem. Optical angular momentum in a dispersive medium has no simple relation to optical linear momentum, even if the medium is homogeneous. A circularly polarized monochromatic beam in a homogeneous, dispersive medium carries a spin angular momentum per unit energy of $\\pm\\omega^{-1}$, as in vacuum. This result demonstrates the non-trivial interplay of dispersive contributions to optical angular momentum and energy.
AngularJS web application development
Darwin, Peter Bacon
2013-01-01
The book will be a step-by-step guide showing the readers how to build a complete web app with AngularJSJavaScript developers who want to learn AngularJS for developing web apps. Knowledge of JavaScript and HTML is expected. No knowledge of AngularJS is required.
Energy Technology Data Exchange (ETDEWEB)
Vaughn, Mark R. (Albuquerque, NM); Robinett, III, Rush D. (Tijeras, NM); Phelan, John R. (Albuquerque, NM); Van Zuiden, Don M. (Albuquerque, NM)
1997-01-21
A new class of coplanar two-axis angular effectors. These effectors combine a two-axis rotational joint analogous to a Cardan joint with linear actuators in a manner to produce a wider range of rotational motion about both axes defined by the joint. This new class of effectors also allows design of robotic manipulators having very high strength and efficiency. These effectors are particularly suited for remote operation in unknown surroundings, because of their extraordinary versatility. An immediate application is to the problems which arise in nuclear waste remediation.
Energy Technology Data Exchange (ETDEWEB)
Vaughn, M.R.; Robinett, R.D. III; Phelan, J.R.; Zuiden, D.M. Van
1997-01-21
A new class of coplanar two-axis angular effectors is described. These effectors combine a two-axis rotational joint analogous to a Cardan joint with linear actuators in a manner to produce a wider range of rotational motion about both axes defined by the joint. This new class of effectors also allows design of robotic manipulators having very high strength and efficiency. These effectors are particularly suited for remote operation in unknown surroundings, because of their extraordinary versatility. An immediate application is to the problems which arise in nuclear waste remediation. 11 figs.
Berenbaum, M; Feeny, P
1981-05-22
Xanthotoxin, a linear furanocoumarin occurring in many plants of the family Umbelliferae, is not appreciably toxic to the umbellifer-feeding larvae of Papilio polyxenes (Lepidoptera; Papilionidae), whereas angelicin, an angular furanocoumarin found only in a few relatively advanced tribes of the Umbelliferae, reduces growth rate and fecundity. The biosynthetic pathway leading to angular attachment of the furan ring may thus have been a response within the Umbelliferae to selective pressures exerted by specialized herbivores that had adapted to feeding on linear furanocoumarins.
A Missile-Borne Angular Velocity Sensor Based on Triaxial Electromagnetic Induction Coils
Directory of Open Access Journals (Sweden)
Jian Li
2016-09-01
Full Text Available Aiming to solve the problem of the limited measuring range for angular motion parameters of high-speed rotating projectiles in the field of guidance and control, a self-adaptive measurement method for angular motion parameters based on the electromagnetic induction principle is proposed. First, a framework with type bent “I-shape” is used to design triaxial coils in a mutually orthogonal way. Under the condition of high rotational speed of a projectile, the induction signal of the projectile moving across a geomagnetic field is acquired by using coils. Second, the frequency of the pulse signal is adjusted self-adaptively. Angular velocity and angular displacement are calculated in the form of periodic pulse counting and pulse accumulation, respectively. Finally, on the basis of that principle prototype of the sensor is researched and developed, performance of measuring angular motion parameters are tested on the sensor by semi-physical and physical simulation experiments, respectively. Experimental results demonstrate that the sensor has a wide measuring range of angular velocity from 1 rps to 100 rps with a measurement error of less than 0.3%, and the angular displacement measurement error is lower than 0.2°. The proposed method satisfies measurement requirements for high-speed rotating projectiles with an extremely high dynamic range of rotational speed and high precision, and has definite value to engineering applications in the fields of attitude determination and geomagnetic navigation.
Transverse and longitudinal angular momenta of light
Bliokh, Konstantin Y
2015-01-01
We review basic physics and novel types of optical angular momentum. We start with a theoretical overview of momentum and angular momentum properties of generic optical fields, and discuss methods for their experimental measurements. In particular, we describe the well-known longitudinal (i.e., aligned with the mean momentum) spin and orbital angular momenta in polarized vortex beams. Then, we focus on the transverse (i.e., orthogonal to the mean momentum) spin and orbital angular momenta, which were recently actively discussed in theory and observed in experiments. First, the recently-discovered transverse spin angular momenta appear in various structured fields: evanescent waves, interference fields, and focused beams. We show that there are several kinds of transverse spin angular momentum, which differ strongly in their origins and physical properties. We describe extraordinary features of the transverse optical spins and overview recent experiments. In particular, the helicity-independent transverse spin...
Oral candidiasis and angular cheilitis.
Sharon, Victoria; Fazel, Nasim
2010-01-01
Candidiasis, an often encountered oral disease, has been increasing in frequency. Most commonly caused by the overgrowth of Candida albicans, oral candidiasis can be divided into several categories including acute and chronic forms, and angular cheilitis. Risk factors for the development of oral candidiasis include immunosuppression, wearing of dentures, pharmacotherapeutics, smoking, infancy and old age, endocrine dysfunction, and decreased salivation. Oral candidiasis may be asymptomatic. More frequently, however, it is physically uncomfortable, and the patient may complain of burning mouth, dysgeusia, dysphagia, anorexia, and weight loss, leading to nutritional deficiency and impaired quality of life. A plethora of antifungal treatments are available. The overall prognosis of oral candidiasis is good, and rarely is the condition life threatening with invasive or recalcitrant disease.
Angular Distributions as Lifetime Probes
Dror, Jeff Asaf
2013-01-01
If new TeV scale particles are discovered, it will be important to determine their width. There is, however, a problematic region, where the width is too small to be determined directly, and too large to generate a secondary vertex. For a collection of colored, spin polarized particles, hadronization depolarizes the particles prior to their decay. The amount of depolarization can be used to probe the lifetime in the problematic region. In this paper we apply this method to a realistic scenario of a top-like particle that can be produced at the LHC. We study how depolarization affects the angular distributions of the decay products and derive an equation for the distributions that is sensitive to the lifetime.
Chirality and the angular momentum of light
Cameron, Robert P.; Götte, Jörg B.; Barnett, Stephen M.; Yao, Alison M.
2017-02-01
Chirality is exhibited by objects that cannot be rotated into their mirror images. It is far from obvious that this has anything to do with the angular momentum of light, which owes its existence to rotational symmetries. There is nevertheless a subtle connection between chirality and the angular momentum of light. We demonstrate this connection and, in particular, its significance in the context of chiral light-matter interactions. This article is part of the themed issue 'Optical orbital angular momentum'.
A Novel Permanent Magnetic Angular Acceleration Sensor
Hao Zhao; Hao Feng
2015-01-01
Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating system, which enables convenient sensor installation. For the cup structure of the sensor rotor, it h...
Magnetic Modulation of Stellar Angular Momentum Loss
Garraffo, Cecilia; Cohen, Ofer
2014-01-01
Angular Momentum Loss is important for understanding astrophysical phenomena such as stellar rotation, magnetic activity, close binaries, and cataclysmic variables. Magnetic breaking is the dominant mechanism in the spin down of young late-type stars. We have studied angular momentum loss as a function of stellar magnetic activity. We argue that the complexity of the field and its latitudinal distribution are crucial for angular momentum loss rates. In this work we discuss how angular momentum is modulated by magnetic cycles, and how stellar spin down is not just a simple function of large scale magnetic field strength.
Transverse and longitudinal angular momenta of light
Energy Technology Data Exchange (ETDEWEB)
Bliokh, Konstantin Y., E-mail: k.bliokh@gmail.com [Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama 351-0198 (Japan); Nonlinear Physics Centre, RSPhysE, The Australian National University, Canberra, ACT 0200 (Australia); Nori, Franco [Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama 351-0198 (Japan); Physics Department, University of Michigan, Ann Arbor, MI 48109-1040 (United States)
2015-08-26
We review basic physics and novel types of optical angular momentum. We start with a theoretical overview of momentum and angular momentum properties of generic optical fields, and discuss methods for their experimental measurements. In particular, we describe the well-known longitudinal (i.e., aligned with the mean momentum) spin and orbital angular momenta in polarized vortex beams. Then, we focus on the transverse (i.e., orthogonal to the mean momentum) spin and orbital angular momenta, which were recently actively discussed in theory and observed in experiments. First, the recently-discovered transverse spin angular momenta appear in various structured fields: evanescent waves, interference fields, and focused beams. We show that there are several kinds of transverse spin angular momentum, which differ strongly in their origins and physical properties. We describe extraordinary features of the transverse optical spins and overview recent experiments. In particular, the helicity-independent transverse spin inherent in edge evanescent waves offers robust spin–direction coupling at optical interfaces (the quantum spin Hall effect of light). Second, we overview the transverse orbital angular momenta of light, which can be both extrinsic and intrinsic. These two types of the transverse orbital angular momentum are produced by spatial shifts of the optical beams (e.g., in the spin Hall effect of light) and their Lorentz boosts, respectively. Our review is underpinned by a unified theory of the angular momentum of light based on the canonical momentum and spin densities, which avoids complications associated with the separation of spin and orbital angular momenta in the Poynting picture. It allows us to construct a comprehensive classification of all known optical angular momenta based on their key parameters and main physical properties.
Quantum Correlation Coefficients for Angular Coherent States
Institute of Scientific and Technical Information of China (English)
CHEN Wei; HE Yan; GUO Hao
2009-01-01
Quantum covariance and correlation coefficients of angular or SU(2) coherent states are directly calculated for all irreducible unitary representations.These results explicitly verify that the angular coherent states minimize the Robertson-Schrodinger uncertainty relation for all spins, which means that they are the so-called intelligent states.The same results can be obtained by the Schwinger representation approach.
Angular Momentum Eigenstates for Equivalent Electrons.
Tuttle, E. R.; Calvert, J. B.
1981-01-01
Simple and efficient methods for adding angular momenta and for finding angular momentum eigenstates for systems of equivalent electrons are developed. Several different common representations are used in specific examples. The material is suitable for a graduate course in quantum mechanics. (SK)
Responsive web design with AngularJS
Patel, Sandeep Kumar
2014-01-01
If you are an AngularJS developer who wants to learn about responsive web application development, this book is ideal for you. Responsive Web Design with AngularJS is intended for web developers or designers with a basic knowledge of HTML, CSS, and JavaScript.
Angular Momentum Distribution in the Transverse Plane
Adhikari, Lekha
2016-01-01
Several possibilities to relate the $t$-dependence of Generalized Parton Distributions (GPDs) to the distribution of angular momentum in the transverse plane are discussed. Using a simple spectator model we demonstrate that non of them correctly describes the orbital angular momentum distribution that for a longitudinally polarized nucleon obtained directly from light-front wavefunctions.
Physical Angular Momentum Separation for QED
Sun, Weimin
2016-01-01
We study the non-uniqueness problem of the gauge-invariant angular momentum separation for the case of QED, which stems from the recent controversy concerning the proper definitions of the orbital angular momentum and spin operator of the individual parts of a gauge field system. For the free quantum electrodynamics without matter, we show that the basic requirement of Euclidean symmetry selects a unique physical angular momentum separation scheme from the multitude of the possible angular momentum separation schemes constructed using the various Gauge Invariant Extentions. Based on these results, we propose a set of natural angular momentum separation schemes for the case of interacting QED by invoking the formalism of asymptotic fields. Some perspectives on such a problem for the case of QCD are briefly discussed.
Novel Detection of Optical Orbital Angular Momentum
2014-11-16
Spreeuw, J. P . Woerdman, “ Orbital angular momentum of light and the transformation of Laguerre-Gaussian laser modes,” Phys. Rev. A, 45(11), 8185-8189...AFRL-RD-PS- AFRL-RD-PS TR-2014-0045 TR-2014-0045 Novel Detection of Optical Orbital Angular Momentum David Voelz Klipsch... Orbital Angular Momentum FA9451-13-1-0261 GR0004113 David Voelz Klipsch School of ECE New Mexico State University MSC 3-O, PO Box 30001 Las Cruces, NM
Radiofrequency encoded angular-resolved light scattering
DEFF Research Database (Denmark)
Buckley, Brandon W.; Akbari, Najva; Diebold, Eric D.
2015-01-01
The sensitive, specific, and label-free classification of microscopic cells and organisms is one of the outstanding problems in biology. Today, instruments such as the flow cytometer use a combination of light scatter measurements at two distinct angles to infer the size and internal complexity...... of cells at rates of more than 10,000 per second. However, by examining the entire angular light scattering spectrum it is possible to classify cells with higher resolution and specificity. Current approaches to performing these angular spectrum measurements all have significant throughput limitations...... Encoded Angular-resolved Light Scattering (REALS), this technique multiplexes angular light scattering in the radiofrequency domain, such that a single photodetector captures the entire scattering spectrum from a particle over approximately 100 discrete incident angles on a single shot basis. As a proof...
Generalized Uncertainty Principle and Angular Momentum
Bosso, Pasquale
2016-01-01
Various models of quantum gravity suggest a modification of the Heisenberg's Uncertainty Principle, to the so-called Generalized Uncertainty Principle, between position and momentum. In this work we show how this modification influences the theory of angular momentum in Quantum Mechanics. In particular, we compute Planck scale corrections to angular momentum eigenvalues, the Hydrogen atom spectrum, the Stern-Gerlach experiment and the Clebsch-Gordan coefficients. We also examine effects of the Generalized Uncertainty Principle on multi-particle systems.
Angular distribution in complex oscillation theory
Institute of Scientific and Technical Information of China (English)
WU Shengjian
2005-01-01
Let f1 and f2 be two linearly independent solutions of the differential equation f" + Af =0,where A is an entire function.Set E-f1f2.In this paper,we shall study the angular distribution of E and establish a relation between zero accumulation rays and Borel directions of E.Consequently we can obtain some results in the complex differential equation by using known results in angular distribution theory of meromorphic functions.
Mastering AngularJD for .NET developers
Majid, Mohammad Wadood
2015-01-01
This book is envisioned for traditional developers and programmers who want to develop client-side applications using the AngularJS framework and ASP.NET Web API 2 with Visual Studio. .NET developers who have already built web applications or web services and who have a fundamental knowledge of HTML, JavaScript, and CSS and want to explore single-page applications will also find this guide useful. Basic knowledge of AngularJS would be helpful.
Geometric absorption of electromagnetic angular momentum
Konz, C.; Benford, Gregory
2003-10-01
Circularly polarized electromagnetic fields carry both energy and angular momentum. We investigate the conditions under which a circularly polarized wave field transfers angular momentum to a perfectly conducting macroscopic object, using exact electromagnetic wave theory in a steady-state calculation. We find that axisymmetric perfect conductors cannot absorb or radiate angular momentum when illuminated. However, any asymmetry allows absorption. A rigorous, steady-state solution of the boundary value problem for the reflection from a perfectly conducting infinite wedge shows that waves convey angular momentum at the edges of asymmetries. Conductors can also radiate angular momentum, so their geometric absorption coefficient for angular momentum can be negative. Such absorption or radiation depends solely on the specific geometry of the conductor. The geometric absorption coefficient can be as high as 0.8, and the coefficient for radiation can be -0.4, larger than typical material absorption coefficients. We apply the results to recent experiments which spun roof-shaped aluminum sheets with polarized microwave beams. Applications of geometric, instead of material, absorption can be quite varied. Though experiments testing these ideas will be simpler at microwavelengths, the ideas work for optical ones as well.
Orbital angular momentum in optical fibers
Bozinovic, Nenad
Internet data traffic capacity is rapidly reaching limits imposed by nonlinear effects of single mode fibers currently used in optical communications. Having almost exhausted available degrees of freedom to orthogonally multiplex data in optical fibers, researchers are now exploring the possibility of using the spatial dimension of fibers, via multicore and multimode fibers, to address the forthcoming capacity crunch. While multicore fibers require complex manufacturing, conventional multi-mode fibers suffer from mode coupling, caused by random perturbations in fibers and modal (de)multiplexers. Methods that have been developed to address the problem of mode coupling so far, have been dependent on computationally intensive digital signal processing algorithms using adaptive optics feedback or complex multiple-input multiple-output algorithms. Here we study the possibility of using the orbital angular momentum (OAM), or helicity, of light, as a means of increasing capacity of future optical fiber communication links. We first introduce a class of specialty fibers designed to minimize mode coupling and show their potential for OAM mode generation in fibers using numerical analysis. We then experimentally confirm the existence of OAM states in these fibers using methods based on fiber gratings and spatial light modulators. In order to quantify the purity of created OAM states, we developed two methods based on mode-image analysis, showing purity of OAM states to be 90% after 1km in these fibers. Finally, in order to demonstrate data transmission using OAM states, we developed a 4-mode multiplexing and demultiplexing systems based on free-space optics and spatial light modulators. Using simple coherent detection methods, we successfully transmit data at 400Gbit/s using four OAM modes at a single wavelength, over 1.1 km of fiber. Furthermore, we achieve data transmission at 1.6Tbit/s using 10 wavelengths and two OAM modes. Our study indicates that OAM light can exist
An orbital angular momentum spectrometer for electrons
Harvey, Tyler; Grillo, Vincenzo; McMorran, Benjamin
2016-05-01
With the advent of techniques for preparation of free-electron and neutron orbital angular momentum (OAM) states, a basic follow-up question emerges: how do we measure the orbital angular momentum state distribution in matter waves? Control of both the energy and helicity of light has produced a range of spectroscopic applications, including molecular fingerprinting and magnetization mapping. Realization of an analogous dual energy-OAM spectroscopy with matter waves demands control of both initial and final energy and orbital angular momentum states: unlike for photons, final state post-selection is necessary for particles that cannot be annihilated. We propose a magnetic field-based mechanism for quantum non-demolition measurement of electron OAM. We show that OAM-dependent lensing is produced by an operator of form U =exp iLzρ2/ℏb2 where ρ =√{x2 +y2 } is the radial position operator, Lz is the orbital angular momentum operator along z, and b is the OAM dispersion length. We can physically realize this operator as a term in the time evolution of an electron in magnetic round lens. We discuss prospects and practical challenges for implementation of a lensing orbital angular momentum measurement. This work was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under the Early Career Research Program Award # DE-SC0010466.
Ultrafast angular momentum transfer in multisublattice ferrimagnets.
Bergeard, N; López-Flores, V; Halté, V; Hehn, M; Stamm, C; Pontius, N; Beaurepaire, E; Boeglin, C
2014-03-11
Femtosecond laser pulses can be used to induce ultrafast changes of the magnetization in magnetic materials. However, one of the unsolved questions is that of conservation of the total angular momentum during the ultrafast demagnetization. Here we report the ultrafast transfer of angular momentum during the first hundred femtoseconds in ferrimagnetic Co0.8Gd0.2 and Co0.74Tb0.26 films. Using time-resolved X-ray magnetic circular dichroism allowed for time-resolved determination of spin and orbital momenta for each element. We report an ultrafast quenching of the magnetocrystalline anisotropy and show that at early times the demagnetization in ferrimagnetic alloys is driven by the local transfer of angular momenta between the two exchange-coupled sublattices while the total angular momentum stays constant. In Co0.74Tb0.26 we have observed a transfer of the total angular momentum to an external bath, which is delayed by ~150 fs.
Data-oriented development with AngularJS
Waikar, Manoj
2015-01-01
This book helps beginner-level AngularJS developers organize AngularJS applications by discussing important AngularJS concepts and best practices. If you are an experienced AngularJS developer but haven't written directives or haven't created custom HTML controls before, then this book is ideal for you.
Localizing the Angular Momentum of Linear Gravity
Butcher, Luke M; Hobson, Michael; 10.1103/PhysRevD.86.084012
2012-01-01
In a previous article [Phys. Rev. D 82 104040 (2010)], we derived an energy-momentum tensor for linear gravity that exhibited positive energy density and causal energy flux. Here we extend this framework by localizing the angular momentum of the linearized gravitational field, deriving a gravitational spin tensor which possesses similarly desirable properties. By examining the local exchange of angular momentum (between matter and gravity) we find that gravitational intrinsic spin is localized, separately from orbital angular momentum, in terms of a gravitational spin tensor. This spin tensor is then uniquely determined by requiring that it obey two simple physically motivated algebraic conditions. Firstly, the spin of an arbitrary (harmonic-gauge) gravitational plane wave is required to flow in the direction of propagation of the wave. Secondly, the spin tensor of any transverse-traceless gravitational field is required to be traceless. (The second condition ensures that local field redefinitions suffice to ...
Physics from Angular Projection of Rectangular Grids
Singh, Ashmeet
2015-01-01
In this paper, we present a mathematical model for the angular projection of a rectangular arrangement of points in a grid. This simple, yet interesting problem, has both a scholarly value and applications for data extraction techniques to study the physics of various systems. Our work can interest undergraduate students to understand subtle points in the angular projection of a grid and describes various quantities of interest in the projection with completeness and sufficient rigour. We show that for certain angular ranges, the projection has non-distinctness, and calculate the details of such angles, and correspondingly, the number of distinct points and the total projected length. We focus on interesting trends obtained for the projected length of the grid elements and present a simple application of the model to determine the geometry of an unknown grid whose spatial extensions are known, using measurement of the grid projection at two angles only. Towards the end, our model is shown to have potential ap...
Angular momentum transport in protostellar discs
Salmeron, Roberto Aureliano; Wardle, M; Salmeron, Raquel; Konigl, Arieh; Wardle, Mark
2006-01-01
Angular momentum transport in protostellar discs can take place either radially, through turbulence induced by the magnetorotational instability (MRI), or vertically, through the torque exerted by a large-scale magnetic field that threads the disc. Using semi-analytic and numerical results, we construct a model of steady-state discs that includes vertical transport by a centrifugally driven wind as well as MRI-induced turbulence. We present approximate criteria for the occurrence of either one of these mechanisms in an ambipolar diffusion-dominated disc. We derive ``strong field'' solutions in which the angular momentum transport is purely vertical and ``weak field'' solutions that are the stratified-disc analogues of the previously studied MRI channel modes; the latter are transformed into accretion solutions with predominantly radial angular-momentum transport when we implement a turbulent-stress prescription based on published results of numerical simulations. We also analyze ``intermediate field strength'...
Surface angular momentum of light beams.
Ornigotti, Marco; Aiello, Andrea
2014-03-24
Traditionally, the angular momentum of light is calculated for "bullet-like" electromagnetic wave packets, although in actual optical experiments "pencil-like" beams of light are more commonly used. The fact that a wave packet is bounded transversely and longitudinally while a beam has, in principle, an infinite extent along the direction of propagation, renders incomplete the textbook calculation of the spin/orbital separation of the angular momentum of a light beam. In this work we demonstrate that a novel, extra surface part must be added in order to preserve the gauge invariance of the optical angular momentum per unit length. The impact of this extra term is quantified by means of two examples: a Laguerre-Gaussian and a Bessel beam, both circularly polarized.
Angular momentum transfer in incomplete fusion
Indian Academy of Sciences (India)
B S Tomar; K Surendra Babu; K Sudarshan; R Tripathi; A Goswami
2005-02-01
Isomeric cross-section ratios of evaporation residues formed in 12C+93Nb and 16O + 89Y reactions were measured by recoil catcher technique followed by off-line -ray spectrometry in the beam energy range of 55.7-77.5 MeV for 12C and 68-81 MeV for 16O. The isomeric cross-section ratios were resolved into that for complete and incomplete fusion reactions. The angular momentum of the intermediate nucleus formed in incomplete fusion was deduced from the isomeric cross-section ratio by considering the statistical de-excitation of the incompletely fused composite nucleus. The data show that incomplete fusion is associated with angular momenta slightly smaller than critical angular momentum for complete fusion, indicating the deeper interpenetration of projectile and target nuclei than that in peripheral collisions.
Ghost Imaging Using Orbital Angular Momentum
Institute of Scientific and Technical Information of China (English)
赵生妹; 丁建; 董小亮; 郑宝玉
2011-01-01
We present a novel encoding scheme in a ghost-imaging system using orbital angular momentum. In the signal arm, object spatial information is encoded as a phase matrix. For an N-grey-scale object, different phase matrices, varying from 0 to K with increment n/N, are used for different greyscales, and then they are modulated to a signal beam by a spatial light modulator. According to the conservation of the orbital angular momentum in the ghost imaging system, these changes will give different coincidence rates in measurement, and hence the object information can be extracted in the idler arm. By simulations and experiments, the results show that our scheme can improve the resolution of the image effectively. Compared with another encoding method using orbital angular momentum, our scheme has a better performance for both characters and the image object.%We present a novel encoding scheme in a ghost-imaging system using orbital angular momentum.In the signal arm,object spatial information is encoded as a phase matrix.For an N-grey-scale object,different phase matrices,varying from 0 to π with increment π/N,are used for different greyscales,and then they are modulated to a signal beam by a spatial light modulator.According to the conservation of the orbital angular momentum in the ghost imaging system,these changes will give different coincidence rates in measurement,and hence the object information can be extracted in the idler arm.By simulations and experiments,the results show that our scheme can improve the resolution of the image effectively.Compared with another encoding method using orbital angular momentum,our scheme has a better performance for both characters and the image object.
On the vector model of angular momentum
Saari, Peeter
2016-09-01
Instead of (or in addition to) the common vector diagram with cones, we propose to visualize the peculiarities of quantum mechanical angular momentum by a completely quantized 3D model. It spotlights the discrete eigenvalues and noncommutativity of components of angular momentum and corresponds to outcomes of measurements—real or computer-simulated. The latter can be easily realized by an interactive worksheet of a suitable program package of algebraic calculations. The proposed complementary method of visualization helps undergraduate students to better understand the counterintuitive properties of this quantum mechanical observable.
Concepts of radial and angular kinetic energies
DEFF Research Database (Denmark)
Dahl, Jens Peder; Schleich, W.P.
2002-01-01
We consider a general central-field system in D dimensions and show that the division of the kinetic energy into radial and angular parts proceeds differently in the wave-function picture and the Weyl-Wigner phase-space picture, Thus, the radial and angular kinetic energies are different quantiti...... in the two pictures, containing different physical information, but the relation between them is well defined. We discuss this relation and illustrate its nature by examples referring to a free particle and to a ground-state hydrogen atom....
Angular momentum and the electromagnetic top
Indian Academy of Sciences (India)
GIANFRANCO SPAVIERI; GEORGE T GILLIES
2016-08-01
The electric charge–magnetic dipole interaction is considered. If $\\Gamma_{\\rm em}$ is the electromagnetic and $\\Gamma_{\\rm mech}$ the mechanical angular momentum, the conservation law for the total angular momentum $\\Gamma_{\\rm tot}$ holds: $\\Gamma_{\\rm tot}$ =$\\Gamma_{\\rm em}$ + $\\Gamma_{\\rm mech}$ = ${\\rm const.}$, but when the dipole moment varies with time, $\\Gamma_{\\rm mech}$ is not conserved. We show that the non-conserved $\\Gamma_{\\rm mech}$ of such a macroscopic isolated system might be experimentally observable. With advanced technology, the strength of the interaction hints to the possibility of novel applications for gyroscopes, such as the electromagnetic top.
Orbital angular momentum in the nucleons
Lorcé, Cédric
2014-01-01
In the last decade, it has been realized that the orbital angular momentum of partons inside the nucleon plays a major role. It contributes significantly to nucleon properties and is at the origin of many asymmetries observed in spin physics. It is therefore of paramount importance to determine this quantity if we want to understand the nucleon internal structure and experimental observables. This triggered numerous discussions and controversies about the proper definition of orbital angular momentum and its extraction from experimental data. We summarize the present situation and discuss recent developments in this field.
Angular gyrus syndrome mimicking depressive pseudodementia.
Nagaratnam, Nages; Phan, Tai Anh; Barnett, Claire; Ibrahim, Neamat
2002-09-01
A 67-year-old left-handed woman with a diagnosis of pseudodementia was being treated for depression with little benefit. Neuropsychological evaluations revealed features of angular gyrus syndrome, namely, agraphia, alexia, Gerstmann's syndrome and behavioural manifestations such as depression, poor memory, frustration and irritability. A computed tomographic scan showed a right occipito-temporal infarction, which had occurred 18 months earlier. The patient demonstrated aspects of language dysfunction associated with the syndrome and showed reversed lateralization of cerebral functions. Recognizing and distinguishing between angular gyrus syndrome and depression is important because the appropriate therapies differ. The use of the term pseudodementia can be misleading.
Barbosa, Marcelo
A review about the nuclear properties, namely the nuclear moments (magnetic dipole moment and electric quadrupole moment) and their interaction with electromagnetic fields external to the nucleus (hyperfine interactions), as well as the angular distribution of radiation produced by $\\gamma$-decay, is presented. A detailed description about the theory of Perturbed Angular Correlations was done, including the comparison between $\\gamma-\\gamma$- correlations and $e^{-}- \\gamma$ correlations. For dynamic nuclear interactions, an introduction to the theory of stochastic states in PAC was performed. We focused on ab-initio implementation of observables for analyzing fluctuating quadrupole hyperfine interactions on time dependent perturbed angular correlations experiments. The development of computacional codes solving the full problem, adapted to fit data obtained on single crystals or polycrystals for two-state transient fields with any axial symmetry and orientation was the main purpose of this work. The final pa...
Optimal method for exoplanet detection by angular differential imaging.
Mugnier, Laurent M; Cornia, Alberto; Sauvage, Jean-François; Rousset, Gérard; Fusco, Thierry; Védrenne, Nicolas
2009-06-01
We propose a novel method for the efficient direct detection of exoplanets from the ground using angular differential imaging. The method combines images appropriately, then uses the combined images jointly in a maximum-likelihood framework to estimate the position and intensity of potential planets orbiting the observed star. It takes into account the mixture of photon and detector noises and a positivity constraint on the planet's intensity. A reasonable detection criterion is also proposed based on the computation of the noise propagation from the images to the estimated intensity of the potential planet. The implementation of this method is tested on simulated data that take into account static aberrations before and after the coronagraph, residual turbulence after adaptive optics correction, and noise.
Angular and linear momentum of excited ferromagnets
Yan, P.; Kamra, A.; Cao, Y.; Bauer, G.E.W.
2013-01-01
The angular momentum vector of a Heisenberg ferromagnet with isotropic exchange interaction is conserved, while under uniaxial crystalline anisotropy the projection of the total spin along the easy axis is a constant of motion. Using Noether's theorem, we prove that these conservation laws persist i
A Novel Permanent Magnetic Angular Acceleration Sensor
Directory of Open Access Journals (Sweden)
Hao Zhao
2015-07-01
Full Text Available Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating system, which enables convenient sensor installation. For the cup structure of the sensor rotor, it has a relatively small rotational inertia. Due to the unique mechanical structure of the sensor, the output signal of the sensor can be directed without a slip ring, which avoids signal weakening effect. In this paper, the operating principle of the sensor is described, and simulated using finite element method. The sensitivity of the sensor is calibrated by torsional pendulum and angle sensor, yielding an experimental result of about 0.88 mV/(rad·s−2. Finally, the angular acceleration of the actual rotating system has been tested, using both a single-phase asynchronous motor and a step motor. Experimental result confirms the operating principle of the sensor and indicates that the sensor has good practicability.
A Novel Permanent Magnetic Angular Acceleration Sensor.
Zhao, Hao; Feng, Hao
2015-07-03
Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating system, which enables convenient sensor installation. For the cup structure of the sensor rotor, it has a relatively small rotational inertia. Due to the unique mechanical structure of the sensor, the output signal of the sensor can be directed without a slip ring, which avoids signal weakening effect. In this paper, the operating principle of the sensor is described, and simulated using finite element method. The sensitivity of the sensor is calibrated by torsional pendulum and angle sensor, yielding an experimental result of about 0.88 mV/(rad·s(-2)). Finally, the angular acceleration of the actual rotating system has been tested, using both a single-phase asynchronous motor and a step motor. Experimental result confirms the operating principle of the sensor and indicates that the sensor has good practicability.
Angular Momentum Transport in Accretion Disks
DEFF Research Database (Denmark)
E. Pessah, Martin; Chan, Chi-kwan; Psaltis, Dimitrios;
2007-01-01
if the resolution were set equal to the natural dissipation scale in astrophysical disks. We conclude that, in order for MRI-driven turbulent angular momentum transport to be able to account for the large value of the effective alpha viscosity inferred observationally, the disk must be threaded by a significant...
ANGULAR MOMENTUM ACQUISITION IN GALAXY HALOS
Energy Technology Data Exchange (ETDEWEB)
Stewart, Kyle R. [Department of Natural and Mathematical Sciences, California Baptist University, 8432 Magnolia Ave., Riverside, CA 92504 (United States); Brooks, Alyson M. [Department of Astronomy, University of Wisconsin-Madison, 475 N. Charter St., Madison, WI 53706 (United States); Bullock, James S. [Center for Cosmology, Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697 (United States); Maller, Ariyeh H. [Department of Physics, New York City College of Technology, 300 Jay St., Brooklyn, NY 11201 (United States); Diemand, Juerg [Institute for Theoretical Physics, University of Zurich, 8057, Zurich (Switzerland); Wadsley, James [Department of Physics and Astronomy, McMaster University, Main Street West, Hamilton L85 4M1 (Canada); Moustakas, Leonidas A. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
2013-05-20
We use high-resolution cosmological hydrodynamic simulations to study the angular momentum acquisition of gaseous halos around Milky-Way-sized galaxies. We find that cold mode accreted gas enters a galaxy halo with {approx}70% more specific angular momentum than dark matter averaged over cosmic time (though with a very large dispersion). In fact, we find that all matter has a higher spin parameter when measured at accretion than when averaged over the entire halo lifetime, and is well characterized by {lambda} {approx} 0.1, at accretion. Combined with the fact that cold flow gas spends a relatively short time (1-2 dynamical times) in the halo before sinking to the center, this naturally explains why cold flow halo gas has a specific angular momentum much higher than that of the halo and often forms ''cold flow disks.'' We demonstrate that the higher angular momentum of cold flow gas is related to the fact that it tends to be accreted along filaments.
Critical gravitational collapse with angular momentum
Gundlach, Carsten
2016-01-01
We derive a theoretical model of mass and angular momentum scaling in type-II critical collapse with rotation. We focus on the case where the critical solution has precisely one, spherically symmetric, unstable mode. We demonstrate excellent agreement with numerical results for critical collapse of a rotating radiation fluid, which falls into this case.
A new method for angular displacement measurement
Institute of Scientific and Technical Information of China (English)
Caini Zhang(张彩妮); Xiangzhao Wang(王向朝)
2003-01-01
We describe a new method for angular displacement measurements that is based on a Fabry-Perot inter-ferometer. A measurement accuracy of 10-s rad is obtained by use of the sinusoidal phase modulatinginterferometry. Another Fabry-Perot interferometer is used to obtain the key initial angle of incidence.
Optical angular momentum conversion in a nanoslit
Chimento, P.F.; Alkemade, P.F.A.; T Hooft, G.W.; Eliel, E.R.
2012-01-01
We demonstrate partial conversion of circularly polarized light into orbital angular momentum-carrying vortex light with opposite-handed circular polarization. This conversion is accomplished in a novel manner using the birefringent properties of a circular subwavelength slit in a thin metal film. O
Wigner Functions and Quark Orbital Angular Momentum
Directory of Open Access Journals (Sweden)
Mukherjee Asmita
2015-01-01
Full Text Available Wigner distributions contain combined position and momentum space information of the quark distributions and are related to both generalized parton distributions (GPDs and transverse momentum dependent parton distributions (TMDs. We report on a recent model calculation of the Wigner distributions for the quark and their relation to the orbital angular momentum.
γ - γ Angular Correlation Measurements With GRIFFIN
Maclean, Andrew; Griffin Collaboration
2015-10-01
When an excited nuclear state emits successive γ-rays causing a γ - γ cascade an anisotropy is found in the spatial distribution of γ2 with respect to γ1. Defining the direction of γ1 as the z-axis, the intermediate level, in general will have an uneven distribution of m-states. This causes an anisotropy in the angular correlation of the second γ-ray with respect to the first. These angular correlations are expressed by the W (θ) that depends on numerical coefficients described by the sequence of spin-parity values for the nuclear states involved, the multipolarities and mixing ratios. Angular correlations can be used for the assignment of spins and parities for the nuclear states, and thus provide a powerful means to elucidate the structure of nuclei far from stability through β - γ - γ coincidence measurements. In order to explore the sensitivity of the new 16 clover-detector GRIFFIN γ-ray spectrometer at TRIUMF-ISAC to such γ - γ angular correlations, and to optimize its performance for these measurements we have studied a well known γ - γ cascade from 60Co decay through both experimental measurements and Geant4 simulation. Results will be shown in this talk. Work supported by the Canada Foundation for Innovation, the Natural Sciences and Engineering Research Council of Canada and the National Research Council of Canada.
On the quantisation of the angular momentum
Ho, V B
1994-01-01
When a hydrogen-like atom is treated as a two dimensional system whose configuration space is multiply connected, then in order to obtain the same energy spectrum as in the Bohr model the angular momentum must be half-integral.
Oral medicine in practice: angular cheilitis.
Lamey, P J; Lewis, M A
1989-07-08
In a series of twelve articles the authors aim to cover the more common oral medicine problems likely to be encountered in dental practice. Whenever possible, clinical photographs have been used to illustrate important points, and the text is deliberately succinct and without references. In the first article, the pathogenesis, investigation and management of angular cheilitis is reviewed.
Angular vibration measurement using grating and laser interferometer
Zhang, Li; Peng, Jun
2006-06-01
Primary angular acceleration calibration standard is developed by CIMM to generate standard rotational angle, angular velocity and angular acceleration, which are traceable to the International System of Units (SI). It can be used to calibrate angular transducers, i.e. angular accelerometer, angular velocity transducer, and rotational angle transducer to obtain amplitude sensitivity and phase shift by sinusoidal vibration. The measurement systems based on grating and laser interferometers are introduced in this paper. The measurement system based on PXI bus instrument is used to control the angular exciter, measure the output signal of the laser interferometers and the transducer to be calibrated synchronously. The methods for calculating the amplitude and phase of sinusoidal angular movement are investigated and high performance has been achieved. It shows the standard can be used in angular movement calibration in the frequency range from 0.1Hz to 200Hz.
Zhang, Zijing; Qiao, Tianyuan; Ma, Kun; Cen, Longzhu; Zhang, Jiandong; Wang, Feng; Zhao, Yuan
2016-08-15
Photon orbital angular momentum has led to many novel insights and applications in quantum measurement. Photon orbital angular momentum can increase the resolution and sensitivity of angular rotation measurement. However, quantum measurement strategy can further surpass this limit and improve the resolution of angular rotation measurement. This Letter proposes and demonstrates a parity measurement method in angular rotation measurement scheme for the first time. Parity measurement can make the resolution superior to the limit of the existing method. The sensitivity can be improved with higher orbital angular momentum photons. Moreover, this Letter gives a detailed discussion of the change of resolution and sensitivity in the presence of photon loss.
Mass and Angular Momentum in General Relativity
Jaramillo, J L
2010-01-01
We present an introduction to mass and angular momentum in General Relativity. After briefly reviewing energy-momentum for matter fields, first in the flat Minkowski case (Special Relativity) and then in curved spacetimes with or without symmetries, we focus on the discussion of energy-momentum for the gravitational field. We illustrate the difficulties rooted in the Equivalence Principle for defining a local energy-momentum density for the gravitational field. This leads to the understanding of gravitational energy-momentum and angular momentum as non-local observables that make sense, at best, for extended domains of spacetime. After introducing Komar quantities associated with spacetime symmetries, it is shown how total energy-momentum can be unambiguously defined for isolated systems, providing fundamental tests for the internal consistency of General Relativity as well as setting the conceptual basis for the understanding of energy loss by gravitational radiation. Finally, several attempts to formulate q...
Angular MET sensor for precise azimuth determination
Zaitsev, Dmitry; Antonov, Alexander; Krishtop, Vladimir
2016-12-01
This paper describes using a MET-based low-noise angular motion sensor to precisely determine azimuth direction in a dynamic-scheme method of measuring Earth's rotation velocity vector. The scheme includes installing a sensor on a rotating platform so that it could scan a space and seek for the position of highest Earth's rotation vector projection on its axis. This method is very efficient provided a low-noise sensor is used. We take a low-cost angular sensor based on MET (molecular electronic transduction) technology. Sensors of this kind were originally developed for the seismic activity monitoring and are well-known for very good noise performance and high sensitivity. This approach, combined with use of special signal processing algorithms, allowed for reaching the accuracy of 0.07° for a measurement time of 200 seconds.
Angular momentum in cluster Spherical Collapse Model
Cupani, Guido; Mardirossian, Fabio
2011-01-01
Our new formulation of the Spherical Collapse Model (SCM-L) takes into account the presence of angular momentum associated with the motion of galaxy groups infalling towards the centre of galaxy clusters. The angular momentum is responsible for an additional term in the dynamical equation which is useful to describe the evolution of the clusters in the non-equilibrium region which is investigated in the present paper. Our SCM-L can be used to predict the profiles of several strategic dynamical quantities as the radial and tangential velocities of member galaxies, and the total cluster mass. A good understanding of the non-equilibrium region is important since it is the natural scenario where to study the infall in galaxy clusters and the accretion phenomena present in these objects. Our results corroborate previous estimates and are in very good agreement with the analysis of recent observations and of simulated clusters.
CMB Anisotropies Total Angular Momentum Method
Hu, W; Hu, Wayne; White, Martin
1997-01-01
A total angular momentum representation simplifies the radiation transport problem for temperature and polarization anisotropy in the CMB. Scattering terms couple only the quadrupole moments of the distributions and each moment corresponds directly to the observable angular pattern on the sky. We develop and employ these techniques to study the general properties of anisotropy generation from scalar, vector and tensor perturbations to the metric and the matter, both in the cosmological fluids and from any seed perturbations (e.g.~defects) that may be present. The simpler, more transparent form and derivation of the Boltzmann equations brings out the geometric and model-independent aspects of temperature and polarization anisotropy formation. Large angle scalar polarization provides a robust means to distinguish between isocurvature and adiabatic models for structure formation in principle. Vector modes have the unique property that the CMB polarization is dominated by magnetic type parity at small angles and ...
The Cosmology Large Angular Scale Surveyor
Marriage, Tobias; Ali, A.; Amiri, M.; Appel, J. W.; Araujo, D.; Bennett, C. L.; Boone, F.; Chan, M.; Cho, H.; Chuss, D. T.; Colazo, F.; Crowe, E.; Denis, K.; Dünner, R.; Eimer, J.; Essinger-Hileman, T.; Gothe, D.; Halpern, M.; Harrington, K.; Hilton, G.; Hinshaw, G. F.; Huang, C.; Irwin, K.; Jones, G.; Karakla, J.; Kogut, A. J.; Larson, D.; Limon, M.; Lowry, L.; Mehrle, N.; Miller, A. D.; Miller, N.; Moseley, S. H.; Novak, G.; Reintsema, C.; Rostem, K.; Stevenson, T.; Towner, D.; U-Yen, K.; Wagner, E.; Watts, D.; Wollack, E.; Xu, Z.; Zeng, L.
2014-01-01
Some of the most compelling inflation models predict a background of primordial gravitational waves (PGW) detectable by their imprint of a curl-like "B-mode" pattern in the polarization of the Cosmic Microwave Background (CMB). The Cosmology Large Angular Scale Surveyor (CLASS) is a novel array of telescopes to measure the B-mode signature of the PGW. By targeting the largest angular scales (>2°) with a multifrequency array, novel polarization modulation and detectors optimized for both control of systematics and sensitivity, CLASS sets itself apart in the field of CMB polarization surveys and opens an exciting new discovery space for the PGW and inflation. This poster presents an overview of the CLASS project.
Quantum Entanglement of Very High Angular Momenta
Fickler, Robert; Plick, William N; Krenn, Mario; Schaeff, Christoph; Ramelow, Sven; Zeilinger, Anton
2012-01-01
Single photons with helical phase structure may carry a quantized amount of orbital angular momentum (OAM) and are of great interest in quantum information science and fundamental tests of quantum theory. Since there is no theoretical upper limit on how many quanta of OAM a single photon can carry, those systems offer the possibility to create superpositions for one particle and entanglement between two particles with an arbitrary high difference in the quantum number. By transferring polarization entanglement to the OAM degree-of-freedom with an interferometric scheme, we created and observed entanglement up to $600\\bar{h}$ difference in the orbital angular momentum. To our knowledge, we have thus demonstrated entanglement of the highest quantum number in any experiment so far. The only restrictive factor towards even higher numbers arises due to current technical limitations. Furthermore, we show experimentally that the entanglement of very high OAM can be used to improve applications, like the sensitivity ...
Bell inequalities with continuous angular variables
Borges, Carolina V S; Keller, Arne
2011-01-01
We consider bipartite quantum systems characterized by a continuous angular variable \\theta \\in [-\\pi, \\pi[, representing, for instance, the position of a particle on a circle. We show how to reveal non-locality on this type of system using inequalities similar to CHSH ones, originally derived for bipartite spin 1/2 like systems. Such inequalities involve correlated measurement of continuous angular functions and are equivalent to the continuous superposition of CHSH inequalities acting on bidimensional subspaces of the infinite dimensional Hilbert space. As an example, we discuss in detail one application of our results, and we derive inequalities based on orientation correlation measurements. The introduced Bell-type inequalities open the perspective of new and simpler experiments to test non locality on a variety of quantum systems described by continuous variables.
Coherent Control of Photoelectron Wavepacket Angular Interferograms
Hockett, Paul; Wollenhaupt, Matthias; Baumert, Thomas
2015-01-01
Coherent control over photoelectron wavepackets, via the use of polarization-shaped laser pulses, can be understood as a time and polarization-multiplexed process. In this work, we investigate this multiplexing via computation of the observable photoelectron angular interferograms resulting from multi-photon atomic ionization with polarization-shaped laser pulses. We consider the polarization sensitivity of both the instantaneous and cumulative continuum wavefunction; the nature of the cohere...
Angular resolution of stacked resistive plate chambers
Samuel, Deepak; Murgod, Lakshmi P
2016-01-01
We present here detailed derivations of mathematical expressions for the angular resolution of a set of stacked resistive plate chambers (RPCs). The expressions are validated against experimental results using data collected from the prototype detectors (without magnet) of the upcoming India-based Neutrino Observatory (INO). In principle, these expressions can be used for any other detector with an architecture similar to that of RPCs.
Angular Momentum Sharing in Dissipative Collisions
Casini, G.; Poggi, G.; Bini, M.; Calamai, S.; Maurenzig, P. R.; Olmi, A.; Pasquali, G.; Stefanini, A. A.; Taccetti, N.; Steckmeyer, J. C.; Laforest, R.; Saint-Laurent, F.
1999-09-01
Light charged particles emitted by the projectilelike fragment were measured in the direct and reverse collision of 93Nb and 116Sn at 25A MeV. The experimental multiplicities of hydrogen and helium particles as a function of the primary mass of the emitting fragment show evidence for a correlation with net mass transfer. The ratio of hydrogen and helium multiplicities points to a dependence of the angular momentum sharing on the net mass transfer.
Angular momentum sharing in dissipative collisions
Casini, G; Bini, M; Calamai, S; Maurenzig, P R; Olmi, A; Pasquali, G; Stefanini, A A; Taccetti, N; Steckmeyer, J C; Laforest, R; Saint-Laurent, F
1999-01-01
Light charged particles emitted by the projectile-like fragment were measured in the direct and reverse collision of $^{93}$Nb and $^{116}$Sn at 25 AMeV. The experimental multiplicities of Hydrogen and Helium particles as a function of the primary mass of the emitting fragment show evidence for a correlation with net mass transfer. The ratio of Hydrogen and Helium multiplicities points to a dependence of the angular momentum sharing on the net mass transfer.
Angular cheilitis, part 1: local etiologies.
Park, Kelly K; Brodell, Robert T; Helms, Stephen E
2011-06-01
Angular cheilitis (AC) is a common condition characterized by erythema, moist maceration, ulceration, and crusting at the corners of the mouth. This article focuses on the common local factors that act alone and in combination to produce AC. These factors are categorized as irritant, allergic, and infectious causes. Identifying the underlying etiology of AC is a critical step in developing an effective treatment plan for this condition.
The Cosmology Large Angular Scale Surveyor
Harrington, Kathleen; Ali, Aamir; Appel, John W; Bennett, Charles L; Boone, Fletcher; Brewer, Michael; Chan, Manwei; Chuss, David T; Colazo, Felipe; Dahal, Sumit; Denis, Kevin; Dünner, Rolando; Eimer, Joseph; Essinger-Hileman, Thomas; Fluxa, Pedro; Halpern, Mark; Hilton, Gene; Hinshaw, Gary F; Hubmayr, Johannes; Iuliano, Jeffery; Karakla, John; McMahon, Jeff; Miller, Nathan T; Moseley, Samuel H; Palma, Gonzalo; Parker, Lucas; Petroff, Matthew; Pradenas, Bastián; Rostem, Karwan; Sagliocca, Marco; Valle, Deniz; Watts, Duncan; Wollack, Edward; Xu, Zhilei; Zeng, Lingzhen
2016-01-01
The Cosmology Large Angular Scale Surveyor (CLASS) is a four telescope array designed to characterize relic primordial gravitational waves from inflation and the optical depth to reionization through a measurement of the polarized cosmic microwave background (CMB) on the largest angular scales. The frequencies of the four CLASS telescopes, one at 38 GHz, two at 93 GHz, and one dichroic system at 145/217 GHz, are chosen to avoid spectral regions of high atmospheric emission and span the minimum of the polarized Galactic foregrounds: synchrotron emission at lower frequencies and dust emission at higher frequencies. Low-noise transition edge sensor detectors and a rapid front-end polarization modulator provide a unique combination of high sensitivity, stability, and control of systematics. The CLASS site, at 5200 m in the Chilean Atacama desert, allows for daily mapping of up to 70\\% of the sky and enables the characterization of CMB polarization at the largest angular scales. Using this combination of a broad f...
A neural circuit for angular velocity computation
Directory of Open Access Journals (Sweden)
Samuel B Snider
2010-12-01
Full Text Available In one of the most remarkable feats of motor control in the animal world, some Diptera, such as the housefly, can accurately execute corrective flight maneuvers in tens of milliseconds. These reflexive movements are achieved by the halteres, gyroscopic force sensors, in conjunction with rapidly-tunable wing-steering muscles. Specifically, the mechanosensory campaniform sensilla located at the base of the halteres transduce and transform rotation-induced gyroscopic forces into information about the angular velocity of the fly's body. But how exactly does the fly's neural architecture generate the angular velocity from the lateral strain forces on the left and right halteres? To explore potential algorithms, we built a neuro-mechanical model of the rotation detection circuit. We propose a neurobiologically plausible method by which the fly could accurately separate and measure the three-dimensional components of an imposed angular velocity. Our model assumes a single sign-inverting synapse and formally resembles some models of directional selectivity by the retina. Using multidimensional error analysis, we demonstrate the robustness of our model under a variety of input conditions. Our analysis reveals the maximum information available to the fly given its physical architecture and the mathematics governing the rotation-induced forces at the haltere's end knob.
The Cosmology Large Angular Scale Surveyor (CLASS)
Harrington, Kathleen; Marriange, Tobias; Aamir, Ali; Appel, John W.; Bennett, Charles L.; Boone, Fletcher; Brewer, Michael; Chan, Manwei; Chuss, David T.; Colazo, Felipe; Denis, Kevin; Moseley, Samuel H.; Rostem, Karwan; Wollack, Edward
2016-01-01
The Cosmology Large Angular Scale Surveyor (CLASS) is a four telescope array designed to characterize relic primordial gravitational waves from in ation and the optical depth to reionization through a measurement of the polarized cosmic microwave background (CMB) on the largest angular scales. The frequencies of the four CLASS telescopes, one at 38 GHz, two at 93 GHz, and one dichroic system at 145/217 GHz, are chosen to avoid spectral regions of high atmospheric emission and span the minimum of the polarized Galactic foregrounds: synchrotron emission at lower frequencies and dust emission at higher frequencies. Low-noise transition edge sensor detectors and a rapid front-end polarization modulator provide a unique combination of high sensitivity, stability, and control of systematics. The CLASS site, at 5200 m in the Chilean Atacama desert, allows for daily mapping of up to 70% of the sky and enables the characterization of CMB polarization at the largest angular scales. Using this combination of a broad frequency range, large sky coverage, control over systematics, and high sensitivity, CLASS will observe the reionization and recombination peaks of the CMB E- and B-mode power spectra. CLASS will make a cosmic variance limited measurement of the optical depth to reionization and will measure or place upper limits on the tensor-to-scalar ratio, r, down to a level of 0.01 (95% C.L.).
Angular cheilitis: a clinical and microbial study.
Ohman, S C; Dahlén, G; Möller, A; Ohman, A
1986-04-01
The purpose of this prospective study was to re-examine the relative importance of various factors in the pathogenesis of angular cheilitis. Sixty-four patients with cheilitis were examined clinically and microbiologically. In addition, a subsample of 23 patients was examined for serum iron and transferrin. The clinical appearance of the lip lesions fell into 4 categories. A ground rhagad at the corner of the mouth involving adjacent skin, was the most frequent type among dentate patients, whereas among denture wearers a deep lesion following the labial marginal sulcus was frequently observed. Dentate patients and denture wearers with cheilitis often had atopic constitution or cutaneous diseases. Pathogenic microorganisms were cultured from the lesions in all 64 patients; Staphylococcus aureus in 40 patients and Candida albicans in 45. The results of this study indicate a correlation between angular cheilitis and pathogenic microorganisms. Furthermore, among dentate patients, a correlation exists between cutaneous discomfort and angular cheilitis. Other etiological factors suggested for this disorder were found to be of subordinate importance.
Schulz, Ulrich; Sierro, Philippe; Nijman, Jint
2008-07-01
The design and implementation of an angular speed control loop for a universal rheometer is not a trivial task. The combination of a highly dynamic, very low inertia (drag cup) motor (motor inertia is 10-5 kg m2) with samples which can range in viscosity from 10-3 Pas to 108 Pas, which can be between purely viscous and higly viscoelastic, which can exhibit yield-stresses, etc. asks for a highly adaptive digital control loop. For the HAAKE MARS rotational rheometer a new adaptive control loop was developed which allows the control of angular speeds as low 5×10-9 rad/s and response times a short as 10 ms. The adaptation of the control loop to "difficult" samples is performed by analysing the response of the complete system to a short pre-test. In this paper we will show that the (very) short response times at (very) low angular speeds are not only achieved with ideal samples, but due to the adaptable control loop, also with "difficult" samples. We will show measurement results on "difficult" samples like cosmetic creams and emulsions, a laponite gel, etc. to proof that angular speeds down to 10-4 rad/s are reached within 10 ms to 20 ms and angular speeds down to 10-7 rad/s within 1 s to 2 s. The response times for reaching ultra low angular speeds down to 5×10-9 rad/s are in the order of 10 s to 30 s. With this new control loop it is, for the first time, possible to measure yield stresses by applying a very low constant shear-rate to the sample and measuring the torque response as a function of time.
Angular momentum of a brane-world model
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
In this paper we discuss the properties of the general covariant angular momentum of a fivedimensional brane-world model. Through calculating the total angular momentum of this model, we are able to analyze the properties of the total angular momentum in the inflationary RS model. We show that the space-like components of the total angular momentum of the inflationary RS model are all zero while the others are non-zero, which agrees with the results from ordinary RS model.
Localization of angular momentum in optical waves propagating through turbulence.
Sanchez, Darryl J; Oesch, Denis W
2011-12-01
This is the first in a series of papers demonstrating that photons with orbital angular momentum can be created in optical waves propagating through distributed turbulence. The scope of this first paper is much narrower. Here, we demonstrate that atmospheric turbulence can impart non-trivial angular momentum to beams and that this non-trivial angular momentum is highly localized. Furthermore, creation of this angular momentum is a normal part of propagation through atmospheric turbulence.
Study of the Angular Distribution of Scintillation Photons
Fornaro, Giulia Alice; Ghezzi, Alessio; Knapitsch, Arno; Modrzynski, Pawel; Pizzichemi, Marco; Lecoq, Paul; Auffray, Etiennette
2014-01-01
This paper presents a characterization method to experimentally determine the angular distribution of scintillation light. By exciting LYSO crystals with a radioactive source, we measured the light angular profiles obtained with samples of different geometries in different conditions of wrapping. We also measured the angular distribution of light emitting in glue and compared it with the one emitting in air. Angular distribution of light output of photonic crystals is also provided. Consistency of the measurements is verified with conventional light output measurements.
Angular Momentum of a Brane-world Model
Jia, Bei; Zhang, Peng-Ming
2008-01-01
In this paper we discuss the properties of the general covariant angular momentum of a five-dimensional brane-world model. Through calculating the total angular momentum of this model, we are able to analyze the properties of the total angular momentum in the inflationary RS model. We show that the space-like components of the total angular momentum of are all zero while the others are non-zero, which agrees with the results from ordinary RS model.
The Cosmology Large Angular Scale Surveyor
Ali, Aamir; Appel, John W.; Bennett, Charles L.; Boone, Fletcher; Brewer, Michael; Chan, Manwei; Chuss, David T.; Colazo, Felipe; Dahal, Sumit; Denis, Kevin; Dünner, Rolando; Eimer, Joseph; Essinger-Hileman, Thomas; Fluxa, Pedro; Halpern, Mark; Hilton, Gene; Hinshaw, Gary F.; Hubmayr, Johannes; Iuliano, Jeffrey; Karakla, John; Marriage, Tobias; McMahon, Jeff; Miller, Nathan; Moseley, Samuel H.; Palma, Gonzalo; Parker, Lucas; Petroff, Matthew; Pradenas, Bastián; Rostem, Karwan; Sagliocca, Marco; Valle, Deniz; Watts, Duncan; Wollack, Edward; Xu, Zhilei; Zeng, Lingzhen
2017-01-01
The Cosmology Large Angular Scale Surveryor (CLASS) is a ground based telescope array designed to measure the large-angular scale polarization signal of the Cosmic Microwave Background (CMB). The large-angular scale CMB polarization measurement is essential for a precise determination of the optical depth to reionization (from the E-mode polarization) and a characterization of inflation from the predicted polarization pattern imprinted on the CMB by gravitational waves in the early universe (from the B-mode polarization). CLASS will characterize the primordial tensor-to-scalar ratio, r, to 0.01 (95% CL).CLASS is uniquely designed to be sensitive to the primordial B-mode signal across the entire range of angular scales where it could possibly dominate over the lensing signal that converts E-modes to B-modes while also making multi-frequency observations both high and low of the frequency where the CMB-to-foreground signal ratio is at its maximum. The design enables CLASS to make a definitive cosmic-variance-limited measurement of the optical depth to scattering from reionization.CLASS is an array of 4 telescopes operating at approximately 40, 90, 150, and 220 GHz. CLASS is located high in the Andes mountains in the Atacama Desert of northern Chile. The location of the CLASS site at high altitude near the equator minimizes atmospheric emission while allowing for daily mapping of ~70% of the sky.A rapid front end Variable-delay Polarization Modulator (VPM) and low noise Transition Edge Sensor (TES) detectors allow for a high sensitivity and low systematic error mapping of the CMB polarization at large angular scales. The VPM, detectors and their coupling structures were all uniquely designed and built for CLASS.We present here an overview of the CLASS scientific strategy, instrument design, and current progress. Particular attention is given to the development and status of the Q-band receiver currently surveying the sky from the Atacama Desert and the development of
Angular Goos-Hänchen effect in curved dielectric microstructures.
Tran, N H; Dutriaux, L; Balcou, P; Floch, A L; Bretenaker, F
1995-06-01
A macroscopic angular Goos-Hänchen effect at total reflection on curved interfaces is studied experimentally. The results are compared with the complex-angular-momentum model of quasi-critical scattering. An extremum in angular deflection, which has not yet been predicted by any theory other than exact Mie scattering computations, is identified at low size parameters.
A critique of the angular momentum sum rules and a new angular momentum sum rule
Bakker, B L G; Trueman, T L
2004-01-01
We show that the expressions in the literature for the tensorial structure of the hadronic matrix elements of the angular momentum operators J are incorrect. Given this disagreement with the published results, we have taken pains to derive the correct expressions in three different ways, two involving explicit physical wave packets and the third, totally independent, based upon the rotational properties of the state vectors. Surprisingly it turns out that the results are very sensitive to the type of relativistic spin state used to describe the motion of the particle i.e. whether a canonical (i.e. boost) state or a helicity state is utilized. We present results for the matrix elements of the angular momentum operators, valid in an arbitrary Lorentz frame, both for helicity states and canonical states. These results are relevant for the construction of angular momentum sum rules, relating the angular momentum of a nucleon to the spin and orbital angular momentum of its constituents. Moreover, we show that it i...
Angular Dispersion and Deflection Function for Heavy Ion Elastic Scattering
Institute of Scientific and Technical Information of China (English)
BAI Zhen; MAO Rui-Shi; YUAN Xiao-Hua; Xu Zhi-Guo; ZHANG Hong-Bin; XU Hua-Gen; QI Hui-Rong; WANG Yue; JIA Fei; WU Li-Jie; DING Xian-Li; WANG Qi; GAO Qi; GAO Hui; LI Song-Lin; LI Jun-Qing; ZHANG Ya-Peng; XIAO Guo-Qing; JIN Gen-Ming; REN Zhong-Zhou; ZHOU Shan-Gui; XU Wang; HAN Jian-Long; Fan Gong-Tao; ZHANG Shuang-Quan; PANG Dan-Yang; SERGEY Yu-Kun; XIAO Zhi-Gang; XU Hu-Shan; SUN Zhi-Yu; HU Zheng-Guo; ZHANG Xue-Ying; WANG Hong-Wei
2007-01-01
The differential cross sections for elastic scattering products of17 F on 208 Pb have been measured.The angular dispersion plots of In(dσ/dθ)versus θ2 are obtained from the angular distribution of the elastic scattering differential cross sections.Systematical analysis on the angular dispersion for the available experimental data indicates that there is an angular dispersion turning angle at forward angular range within the grazing angle.This turning angle can be clarified as nuclear rainbow in classical deflection function.The exotic behaviour of the nuclear rainbow angle offers a new probe to investigate the halo and skin phenomena.
Angular momentum evolution in laser-plasma accelerators
Thaury, C; Corde, S; Lehe, R; Bouteiller, M Le; Phuoc, K Ta; Davoine, X; Rax, J -M; Rousse, A; Malka, V
2013-01-01
The transverse properties of an electron beam are characterized by two quantities, the emittance which indicates the electron beam extend in the phase space and the angular momentum which allows for non-planar electron trajectories. Whereas the emittance of electron beams produced in laser- plasma accelerator has been measured in several experiments, their angular momentum has been scarcely studied. It was demonstrated that electrons in laser-plasma accelerator carry some angular momentum, but its origin was not established. Here we identify one source of angular momentum growth and we present experimental results showing that the angular momentum content evolves during the acceleration.
Angular-momentum evolution in laser-plasma accelerators.
Thaury, C; Guillaume, E; Corde, S; Lehe, R; Le Bouteiller, M; Ta Phuoc, K; Davoine, X; Rax, J M; Rousse, A; Malka, V
2013-09-27
The transverse properties of an electron beam are characterized by two quantities, the emittance which indicates the electron beam extent in the phase space and the angular momentum which allows for nonplanar electron trajectories. Whereas the emittance of electron beams produced in a laser-plasma accelerator has been measured in several experiments, their angular momentum has been scarcely studied. It was demonstrated that electrons in a laser-plasma accelerator carry some angular momentum, but its origin was not established. Here we identify one source of angular-momentum growth and we present experimental results showing that the angular-momentum content evolves during the acceleration.
Angular-Momentum Evolution in Laser-Plasma Accelerators
Thaury, C; Corde, S; Lehe, R; Le Bouteiller, M; Ta Phuoc, K; Davoine, X; Rax, J M; Rousse, A; Malka, V; 10.1103/PhysRevLett.111.135002
2013-01-01
The transverse properties of an electron beam are characterized by two quantities, the emittance which indicates the electron beam extent in the phase space and the angular momentum which allows for nonplanar electron trajectories. Whereas the emittance of electron beams produced in a laser-plasma accelerator has been measured in several experiments, their angular momentum has been scarcely studied. It was demonstrated that electrons in a laser-plasma accelerator carry some angular momentum, but its origin was not established. Here we identify one source of angular-momentum growth and we present experimental results showing that the angular-momentum content evolves during the acceleration.
Electron energy and angular distributions in radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Deasy, J.O.
1992-01-01
Electron energy and angular distributions and associated effects for radiotherapy accelerators and beta-ray ophthalmic applicators have been measured and modeled. Ophthalmic applicator extrapolation chamber calibration geometries were studied using Monte Carlo calculations and analytic methods. A large interface effect increases the surface dose by a factor of about 1.5 and makes very small gap width measurements necessary (0.1--0.2 mm). Dose deposition in tissue near the surface was simulated using the Monte Carlo technique. Charge collection in the extrapolation chamber was analytically modeled on the basis of ionized free electrons back-diffusing into the cathode, while taking into account attachment to O[sub 2] ions. Two small, portable, magnetic spectrometers for the measurement of clinical radiotherapy electron beams were constructed. One employs film as a spectrograph and is suitable for routine measurements; the second is a 90[degree] single-focusing spectrometer and uses fast pulse counting electrons and pulse-height analysis. Spectra were measured for the University of Louisville's Theratronics T20 and Philips SL25 linear accelerators. The T20 spectra were all Gaussian with energy widths of about 5%. The SL25 energy spectra were of varied shapes, with energy widths of 10--20%. Evidence of 3--7% shifts in the average energy of the SL25 beams was observed. Angular measurements were made which showed the Gaussian angular spread of the incident beam. The Monte Carlo code CYLTRAN and measured spectra were used to reconstruct depth dose curves. The peak energy structure only marginally affects the shape of the depth-dose curve, and some features of the depth-dose curves must be affected by incident straggled or widely-scattered electrons. In the absence of lower energy straggled electrons, the range parameters and the maximum dose gradient depend on the mean energy of the peak electrons.
Whole-body angular momentum during stair ascent and descent.
Silverman, Anne K; Neptune, Richard R; Sinitski, Emily H; Wilken, Jason M
2014-04-01
The generation of whole-body angular momentum is essential in many locomotor tasks and must be regulated in order to maintain dynamic balance. However, angular momentum has not been investigated during stair walking, which is an activity that presents a biomechanical challenge for balance-impaired populations. We investigated three-dimensional whole-body angular momentum during stair ascent and descent and compared it to level walking. Three-dimensional body-segment kinematic and ground reaction force (GRF) data were collected from 30 healthy subjects. Angular momentum was calculated using a 13-segment whole-body model. GRFs, external moment arms and net joint moments were used to interpret the angular momentum results. The range of frontal plane angular momentum was greater for stair ascent relative to level walking. In the transverse and sagittal planes, the range of angular momentum was smaller in stair ascent and descent relative to level walking. Significant differences were also found in the ground reaction forces, external moment arms and net joint moments. The sagittal plane angular momentum results suggest that individuals alter angular momentum to effectively counteract potential trips during stair ascent, and reduce the range of angular momentum to avoid falling forward during stair descent. Further, significant differences in joint moments suggest potential neuromuscular mechanisms that account for the differences in angular momentum between walking conditions. These results provide a baseline for comparison to impaired populations that have difficulty maintaining dynamic balance, particularly during stair ascent and descent.
New relativistic Hamiltonian: the angular magnetoelectric coupling
Paillard, Charles; Mondal, Ritwik; Berritta, Marco; Dkhil, Brahim; Singh, Surendra; Oppeneer, Peter M.; Bellaiche, Laurent
2016-10-01
Spin-Orbit Coupling (SOC) is a ubiquitous phenomenon in the spintronics area, as it plays a major role in allowing for enhancing many well-known phenomena, such as the Dzyaloshinskii-Moriya interaction, magnetocrystalline anisotropy, the Rashba effect, etc. However, the usual expression of the SOC interaction ħ/4m2c2 [E×p] • σ (1) where p is the momentum operator, E the electric field, σ the vector of Pauli matrices, breaks the gauge invariance required by the electronic Hamiltonian. On the other hand, very recently, a new phenomenological interaction, coupling the angular momentum of light and magnetic moments, has been proposed based on symmetry arguments: ξ/2 [r × (E × B)] M, (2) with M the magnetization, r the position, and ξ the interaction strength constant. This interaction has been demonstrated to contribute and/or give rise, in a straightforward way, to various magnetoelectric phenomena,such as the anomalous Hall effect (AHE), the anisotropic magnetoresistance (AMR), the planar Hall effect and Rashba-like effects, or the spin-current model in multiferroics. This last model is known to be the origin of the cycloidal spin arrangement in bismuth ferrite for instance. However, the coupling of the angular momentum of light with magnetic moments lacked a fundamental theoretical basis. Starting from the Dirac equation, we derive a relativistic interaction Hamiltonian which linearly couples the angular momentum density of the electromagnetic (EM) field and the electrons spin. We name this coupling the Angular MagnetoElectric (AME) coupling. We show that in the limit of uniform magnetic field, the AME coupling yields an interaction exactly of the form of Eq. (2), thereby giving a firm theoretical basis to earlier works. The AME coupling can be expressed as: ξ [E × A] • σ (3) with A being the vector potential. Interestingly, the AME coupling was shown to be complementary to the traditional SOC, and together they restore the gauge invariance of the
Angular Momentum of Dark Matter Black Holes
Frampton, Paul H
2016-01-01
The putative black holes which may constitute all the dark matter are described by a Kerr metric with only two parameters, mass M and angular momentum J. There has been little discussion of J since it plays no role in the upcoming attempt at detection by microlensing. Nevertheless J does play a central role in understanding the previous lack of detection, especially of CMB distortion. We explain why bounds previously derived from lack of CMB distortion are too strong for primordial black holes with J non-vanishing. Almost none of the dark matter black holes can be from stellar collapse, and nearly all are primordial, to avoid excessive CMB distortion.
Angular Distributions of Discrete Mesoscale Mapping Functions
Directory of Open Access Journals (Sweden)
Kroszczyński Krzysztof
2015-08-01
Full Text Available The paper presents the results of analyses of numerical experiments concerning GPS signal propagation delays in the atmosphere and the discrete mapping functions defined on their basis. The delays were determined using data from the mesoscale non-hydrostatic weather model operated in the Centre of Applied Geomatics, Military University of Technology. A special attention was paid to investigating angular characteristics of GPS slant delays for low angles of elevation. The investigation proved that the temporal and spatial variability of the slant delays depends to a large extent on current weather conditions
Angular momentum evolution of galaxies in EAGLE
Lagos, Claudia del P; Stevens, Adam R H; Cortese, Luca; Padilla, Nelson D; Davis, Timothy A; Contreras, Sergio; Croton, Darren
2016-01-01
We use EAGLE to study the specific angular momentum of galaxies, j, at z1.2, and then increase as lstars~a. Galaxy mergers reduce lstars by a factor of 2-3. These tracks are driven by both the evolution of the total jstars but also its radial distribution. Regardless of the aperture used to measure j, two distinct channels leading to low jstars in galaxies at z=0 are identified: (i) galaxy mergers, and (ii) early formation of most of the stars.
Angular momentum sensitive two-center interference.
Ilchen, M; Glaser, L; Scholz, F; Walter, P; Deinert, S; Rothkirch, A; Seltmann, J; Viefhaus, J; Decleva, P; Langer, B; Knie, A; Ehresmann, A; Al-Dossary, O M; Braune, M; Hartmann, G; Meissner, A; Tribedi, L C; AlKhaldi, M; Becker, U
2014-01-17
In quantum mechanics the Young-type double-slit experiment can be performed with electrons either traveling through a double slit or being coherently emitted from two inversion symmetric molecular sites. In the latter one the valence photoionization cross sections of homonuclear diatomic molecules were predicted to oscillate over kinetic energy almost 50 years ago. Beyond the direct proof of the oscillatory behavior of these photoionization cross sections σ, we show that the angular distribution of the emitted electrons reveals hitherto unexplored information on the relative phase shift between the corresponding partial waves through two-center interference patterns.
Lunar influence on equatorial atmospheric angular momentum
Bizouard, C.; Zotov, L.; Sidorenkov, N.
2015-08-01
This study investigates the relationship between the equatorial atmospheric angular momentum oscillation in the non-rotating frame and lunar tidal potential. Between 2 and 30 days, the corresponding equatorial component is mostly constituted of prograde circular motions, especially of a harmonic at 13.6 days, and of a weekly broad band variation. A simple equilibrium tide model explains the 13.6-day pressure term as result of the O1 lunar tide; the tidal lunar origin of the whole band from 2 to 30 days is attested by specific features, not occurring for seasonal band dominated by the solar thermal effect.
The Cosmology Large Angular Scale Surveyor (CLASS)
Eimer, Joseph; Ali, A.; Amiri, M.; Appel, J. W.; Araujo, D.; Bennett, C. L.; Boone, F.; Chan, M.; Cho, H.; Chuss, D. T.; Colazo, F.; Crowe, E.; Denis, K.; Dünner, R.; Essinger-Hileman, T.; Gothe, D.; Halpern, M.; Harrington, K.; Hilton, G.; Hinshaw, G. F.; Huang, C.; Irwin, K.; Jones, G.; Karakla, J.; Kogut, A. J.; Larson, D.; Limon, M.; Lowry, L.; Marriage, T.; Mehrle, N.; Miller, A. D.; Miller, N.; Moseley, S. H.; Novak, G.; Reintsema, C.; Rostem, K.; Stevenson, T.; Towner, D.; U-Yen, K.; Wagner, E.; Watts, D.; Wollack, E.; Xu, Z.; Zeng, L.
2014-01-01
The Cosmology Large Angular Scale Surveyor (CLASS) is an array of telescopes designed to search for the signature of inflation in the polarization of the Cosmic Microwave Background (CMB). By combining the strategy of targeting large scales (>2 deg) with novel front-end polarization modulation and novel detectors at multiple frequencies, CLASS will pioneer a new frontier in ground-based CMB polarization surveys. In this talk, I give an overview of the CLASS instrument, survey, and outlook on setting important new limits on the energy scale of inflation.
Angular Momentum Sensitive Two-Center Interference
Ilchen, M.; Glaser, L.; Scholz, F.; Walter, P.; Deinert, S.; Rothkirch, A.; Seltmann, J.; Viefhaus, J.; Decleva, P.; Langer, B.; Knie, A.; Ehresmann, A.; Al-Dossary, O. M.; Braune, M.; Hartmann, G.; Meissner, A.; Tribedi, L. C.; AlKhaldi, M.; Becker, U.
2014-01-01
In quantum mechanics the Young-type double-slit experiment can be performed with electrons either traveling through a double slit or being coherently emitted from two inversion symmetric molecular sites. In the latter one the valence photoionization cross sections of homonuclear diatomic molecules were predicted to oscillate over kinetic energy almost 50 years ago. Beyond the direct proof of the oscillatory behavior of these photoionization cross sections σ, we show that the angular distribution of the emitted electrons reveals hitherto unexplored information on the relative phase shift between the corresponding partial waves through two-center interference patterns.
Angular processes related to Cauchy random walks
Cammarota, Valemtina
2011-01-01
We study the angular process related to random walks in the Euclidean and in the non-Euclidean space where steps are Cauchy distributed. This leads to different types of non-linear transformations of Cauchy random variables which preserve the Cauchy density. We give the explicit form of these distributions for all combinations of the scale and the location parameters. Continued fractions involving Cauchy random variables are analyzed. It is shown that the $n$-stage random variables are still Cauchy distributed with parameters related to Fibonacci numbers. This permits us to show the convergence in distribution of the sequence to the golden ratio.
Measurement and analysis of angular velocity variations of twelve-cylinder diesel engine crankshaft
Bulatović, Ž. M.; Štavljanin, M. S.; Tomić, M. V.; Knežević, D. M.; Biočanin, S. Lj.
2011-11-01
This paper presents the procedures for measuring and analyzing the angular velocity variation of twelve-cylinder diesel engine crankshaft on its free end and on the power-output end. In addition, the paper deals with important aspects of the measurement of crankshaft torsional oscillations. The method is based on digital encoders placed at two distances, and one of them is a sensor not inserted directly on the shaft, i.e. a non-contact method with a toothed disc is used. The principle based on toothed disc is also used to measure the actual camshaft angular velocity of in-line compact high-pressure pump the engine is equipped with, and this paper aims to demonstrate the possibility of measuring the actual angular velocity of any rotating shaft in the engine, on which it is physically possible to mount a toothed disc. The method was created completely independently during long-range development and research tests of V46 family engines. This method is specific for its particular adaptability for use on larger engines with extensive vibrations and torsional oscillations. The main purpose of this paper is a practical contribution to all the more interesting research of the use of engine crankshaft angular velocity as a diagnostic tool for identifying the engine irregular running.
CMB anisotropies: Total angular momentum method
Hu, Wayne; White, Martin
1997-07-01
A total angular momentum representation simplifies the radiation transport problem for temperature and polarization anisotropy in the cosmic microwave background (CMB). Scattering terms couple only the quadrupole moments of the distributions and each moment corresponds directly to the observable angular pattern on the sky. We develop and employ these techniques to study the general properties of anisotropy generation from scalar, vector, and tensor perturbations to the metric and the matter, both in the cosmological fluids and from any seed perturbations (e.g., defects) that may be present. The simpler, more transparent form and derivation of the Boltzmann equations brings out the geometric and model-independent aspects of temperature and polarization anisotropy formation. Large angle scalar polarization provides a robust means to distinguish between isocurvature and adiabatic models for structure formation in principle. Vector modes have the unique property that the CMB polarization is dominated by magnetic-type parity at small angles (a factor of 6 in power compared with 0 for the scalars and 8/13 for the tensors) and hence potentially distinguishable independent of the model for the seed. The tensor modes produce a different sign from the scalars and vectors for the temperature-polarization correlations at large angles. We explore conditions under which one perturbation type may dominate over the others including a detailed treatment of the photon-baryon fluid before recombination.
Supramolecular architectures constructed using angular bipyridyl ligands
Barnett, S A
2003-01-01
This work details the synthesis and characterization of a series of coordination frameworks that are formed using bidentate angular N-donor ligands. Pyrimidine was reacted with metal(ll) nitrate salts. Reactions using Cd(NO sub 3) sub 2 receive particular focus and the analogous reactions using the linear ligand, pyrazine, were studied for comparison. In all cases, two-dimensional coordination networks were prepared. Structural diversity is observed for the Cd(ll) centres including metal-nitrate bridging. In contrast, first row transition metal nitrates form isostructural one-dimensional chains with only the bridging N-donor ligands generating polymeric propagation. The angular ligand, 2,4-bis(4-pyridyl)-1,3,5-triazine (dpt), was reacted with Cd(NO sub 3) sub 2 and Zn(NO sub 3) sub 2. Whereas Zn(NO sub 3) sub 2 compounds exhibit solvent mediated polymorphism, a range of structures were obtained for the reactions with Cd(NO sub 3) sub 2 , including the first example of a doubly parallel interpenetrated 4.8 sup...
Detection and recognition of angular frequency patterns.
Wilson, Hugh R; Propp, Roni
2015-05-01
Previous research has extensively explored visual encoding of smoothly curved, closed contours described by sinusoidal variation of pattern radius as a function of polar angle (RF patterns). Although the contours of many biologically significant objects are curved, we also confront shapes with a more jagged and angular appearance. To study these, we introduce here a novel class of visual stimuli that deform smoothly from a circle to an equilateral polygon with N sides (AF patterns). Threshold measurements reveal that both AF and RF patterns can be discriminated from circles at the same deformation amplitude, approximately 18.0arcsec, which is in the hyperacuity range. Thresholds were slightly higher for patterns with 3.0 cycles than for those with 5.0 cycles. Discrimination between AF and RF patterns was 75% correct at an amplitude that was approximately 3.0 times the threshold amplitude, which implies that AF and RF patterns activate different neural populations. Experiments with jittered patterns in which the contour was broken into several pieces and shifted inward or outward had much less effect on AF patterns than on RF patterns. Similarly, thresholds for single angles of AF patterns showed no significant difference from thresholds for the entire AF pattern. Taken together, these results imply that the visual system incorporates angles explicitly in the representation of closed object contours, but it suggests that angular contours are represented more locally than are curved contours.
The angular momentum of a relative equilibrium
Chenciner, Alain
2011-01-01
There are two main reasons why relative equilibria of N point masses under the influence of Newton attraction are mathematically more interesting to study when space dimension is at least 4: On the one hand, in a higher dimensional space, a relative equilibrium is determined not only by the initial configuration but also by the choice of a complex structure on the space where the motion takes place; in particular, its angular momentum depends on this choice; On the other hand, relative equilibria are not necessarily periodic: if the configuration is "balanced" but not central, the motion is in general quasi-periodic. In this exploratory paper we address the following question, which touches both aspects: what are the possible frequencies of the angular momentum of a given central (or balanced) configuration and at what values of these frequencies bifurcations from periodic to quasi-periodic relative equilibria do occur ? We give a full answer for relative equilibrium motions in dimension 4 and conjecture that...
An EM Induction Hi-Speed Rotation Angular Rate Sensor.
Li, Kai; Li, Yuan; Han, Yan
2017-03-17
A hi-speed rotation angular rate sensor based on an electromagnetic induction signal is proposed to provide a possibility of wide range measurement of high angular rates. An angular rate sensor is designed that works on the principle of electromagnetism (EM) induction. In addition to a zero-phase detection technique, this sensor uses the feedback principle of magnetic induction coils in response to a rotating magnetic field. It solves the challenge of designing an angular rate sensor that is suitable for both low and high rotating rates. The sensor was examined for angular rate measurement accuracy in simulation tests using a rotary table. The results show that it is capable of measuring angular rates ranging from 1 rps to 100 rps, with an error within 1.8‰ of the full scale (FS). The proposed sensor is suitable to measurement applications where the rotation angular rate is widely varied, and it contributes to design technology advancements of real-time sensors measuring angular acceleration, angular rate, and angular displacement of hi-speed rotary objects.
Absil, Olivier; 10.1007/s00159-009-0028-y
2009-01-01
The direct images of giant extrasolar planets recently obtained around several main sequence stars represent a major step in the study of planetary systems. These high-dynamic range images are among the most striking results obtained by the current generation of high angular resolution instruments, which will be superseded by a new generation of instruments in the coming years. It is therefore an appropriate time to review the contributions of high angular resolution visible/infrared techniques to the rapidly growing field of extrasolar planetary science. During the last 20 years, the advent of the Hubble Space Telescope, of adaptive optics on 4- to 10-m class ground-based telescopes, and of long-baseline infrared stellar interferometry has opened a new viewpoint on the formation and evolution of planetary systems. By spatially resolving the optically thick circumstellar discs of gas and dust where planets are forming, these instruments have considerably improved our models of early circumstellar environments...
Cepheids at high angular resolution: circumstellar envelope and pulsation
Gallenne, Alexandre
2011-01-01
In 2005, interferometric observations with VLTI/VINCI and CHARA/FLUOR revealed the existence of a circumstellar envelope (CSE) around some Cepheids. This surrounding material is particularly interesting for two reasons: it could have an impact on the distance estimates and could be linked to a past or on-going mass loss. The use of Baade-Wesselink methods for independent distance determinations could be significantly biased by the presence of these envelopes. Although their observations are difficult because of the high contrast between the photosphere of the star and the CSE, several observation techniques have the potential to improve our knowledge about their physical properties. In this thesis, I discuss in particular high angular resolution techniques that I applied to the study of several bright Galactic Cepheids. First, I used adaptive optic observations with NACO of the Cepheid RS Puppis, in order to deduce the flux ratio between the CSE and the photosphere of the star. In addition, I could carry out ...
Electron Energy and Angular Distributions in Radiotherapy.
Deasy, Joseph Owen
1992-01-01
Electron energy and angular distributions and associated effects for radiotherapy accelerators and beta -ray ophthalmic applicators have been measured and modeled. Ophthalmic applicator extrapolation chamber calibration geometries were studied using Monte Carlo calculations and analytic methods. A large interface effect increases the surface dose by a factor of about 1.5 and makes very small gap width measurements necessary (0.1-0.2 mm). Dose deposition in tissue near the surface was simulated using the Monte Carlo technique. Charge collection in the extrapolation chamber was analytically modeled on the basis of ionized free electrons back-diffusing into the cathode, while taking into account attachment to O_2 ions. Previous models underpredict the charge loss, mainly because they assume that all the charge carriers are ions. Two small, portable, magnetic spectrometers for the measurement of clinical radiotherapy electron beams were constructed. One employs film as a spectrograph and is suitable for routine measurements; the second is a 90^circ single-focusing spectrometer and uses fast pulse counting electronics and pulse-height analysis. Tests with monoenergetic electron beams at the National Research Council of Canada's electron linear accelerator showed that the system is free from spectral distortion and verified the spectrometers' energy calibrations. Spectra were measured for the University of Louisville's Theratronics T20 and Philips SL25 linear accelerators. The T20 spectra were all nearly Gaussian in shape with energy widths of about 5%. The SL25 energy spectra were of varied shapes, with energy widths of 10-20%. Evidence of 3-7% shifts in the average energy of the SL25 beams was observed. Angular measurements were made which showed the Gaussian angular spread of the incident beam. The Monte Carlo code CYLTRAN and measured spectra were used to reconstruct depth dose curves. Comparisons with measured depth dose curves show that the peak energy structure
Quantum correlations in optical angle-orbital angular momentum variables.
Leach, Jonathan; Jack, Barry; Romero, Jacqui; Jha, Anand K; Yao, Alison M; Franke-Arnold, Sonja; Ireland, David G; Boyd, Robert W; Barnett, Stephen M; Padgett, Miles J
2010-08-06
Entanglement of the properties of two separated particles constitutes a fundamental signature of quantum mechanics and is a key resource for quantum information science. We demonstrate strong Einstein, Podolsky, and Rosen correlations between the angular position and orbital angular momentum of two photons created by the nonlinear optical process of spontaneous parametric down-conversion. The discrete nature of orbital angular momentum and the continuous but periodic nature of angular position give rise to a special sort of entanglement between these two variables. The resulting correlations are found to be an order of magnitude stronger than those allowed by the uncertainty principle for independent (nonentangled) particles. Our results suggest that angular position and orbital angular momentum may find important applications in quantum information science.
Creating high-harmonic beams with controlled orbital angular momentum.
Gariepy, Genevieve; Leach, Jonathan; Kim, Kyung Taec; Hammond, T J; Frumker, E; Boyd, Robert W; Corkum, P B
2014-10-10
A beam with an angular-dependant phase Φ = ℓϕ about the beam axis carries an orbital angular momentum of ℓℏ per photon. Such beams are exploited to provide superresolution in microscopy. Creating extreme ultraviolet or soft-x-ray beams with controllable orbital angular momentum is a critical step towards extending superresolution to much higher spatial resolution. We show that orbital angular momentum is conserved during high-harmonic generation. Experimentally, we use a fundamental beam with |ℓ| = 1 and interferometrically determine that the harmonics each have orbital angular momentum equal to their harmonic number. Theoretically, we show how any small value of orbital angular momentum can be coupled to any harmonic in a controlled manner. Our results open a route to microscopy on the molecular, or even submolecular, scale.
The SKA as a Doorway to Angular Momentum
Obreschkow, D; Popping, A; Power, C; Quinn, P; Staveley-Smith, L
2015-01-01
Angular momentum is one of the most fundamental physical quantities governing galactic evolution. Differences in the colours, morphologies, star formation rates and gas fractions amongst galaxies of equal stellar/baryon mass M are potentially widely explained by variations in their specific stellar/baryon angular momentum j. The enormous potential of angular momentum science is only just being realised, thanks to the emergence of the first simulations of galaxies with converged spins, paralleled by a dramatic increase in kinematic observations. Such observations are still challenged by the fact that most of the stellar/baryon angular momentum resides at large radii. In fact, the radius that maximally contributes to the angular momentum of an exponential disk (3Re-4Re) is twice as large as the radius that maximally contributes to the disk mass; thus converged measurements of angular momentum require either extremely deep IFS data or, alternatively, kinematic measurements of neutral atomic hydrogen (HI), which ...
Orbital angular momentum photonic quantum interface
Institute of Scientific and Technical Information of China (English)
Zhi-Yuan Zhou; Yan Li; Dong-Sheng Ding; Wei Zhang; Shuai Shi; Bao-Sen Shi; Guang-Can Guo
2016-01-01
Light-carrying orbital angular momentum (OAM) has great potential in enhancing the information channel capacity in both classical and quantum optical communications.Long distance optical communication requires the wavelengths of light are situated in the low-loss communication windows,but most quantum memories currently being developed for use in a quantum repeater work at different wavelengths,so a quantum interface to bridge the wavelength gap is necessary.So far,such an interface for OAM-carried light has not been realized yet.Here,we report the first experimental realization of a quantum interface for a heralded single photon carrying OAM using a nonlinear crystal in an optical cavity.The spatial structures of input and output photons exhibit strong similarity.More importantly,single-photon coherence is preserved during up-conversion as demonstrated.
Four-photon orbital angular momentum entanglement
Hiesmayr, B C; Löffler, W
2015-01-01
Quantum entanglement shared between more than two particles is essential to foundational questions in quantum mechanics, and upcoming quantum information technologies. So far, up to 14 two-dimensional qubits have been entangled, and an open question remains if one can also demonstrate entanglement of higher-dimensional discrete properties of more than two particles. A promising route is the use of the photon orbital angular momentum (OAM), which enables implementation of novel quantum information protocols, and the study of fundamentally new quantum states. To date, only two of such multidimensional particles have been entangled albeit with ever increasing dimensionality. Here we use pulsed spontaneous parametric downconversion (SPDC) to produce photon quadruplets that are entangled in their OAM, or transverse-mode degrees of freedom; and witness genuine multipartite Dicke-type entanglement. Apart from addressing foundational questions, this could find applications in quantum metrology, imaging, and secret sh...
High orbital angular momentum harmonic generation
Vieira, J; Alves, E P; Fonseca, R A; Mendonça, J T; Bingham, R; Norreys, P; Silva, L O
2016-01-01
We identify and explore a high orbital angular momentum (OAM) harmonics generation and amplification mechanism that manipulates the OAM independently of any other laser property, by preserving the initial laser wavelength, through stimulated Raman backscattering in a plasma. The high OAM harmonics spectra can extend at least up to the limiting value imposed by the paraxial approximation. We show with theory and particle-in-cell simulations that the orders of the OAM harmonics can be tuned according to a selection rule that depends on the initial OAM of the interacting waves. We illustrate the high OAM harmonics generation in a plasma using several examples including the generation of prime OAM harmonics. The process can also be realised in any nonlinear optical Kerr media supporting three-wave interactions.
Optical communication beyond orbital angular momentum
Trichili, Abderrahmen; Rosales-Guzmán, Carmelo; Dudley, Angela; Ndagano, Bienvenu; Ben Salem, Amine; Zghal, Mourad; Forbes, Andrew
2016-06-01
Mode division multiplexing (MDM) is mooted as a technology to address future bandwidth issues, and has been successfully demonstrated in free space using spatial modes with orbital angular momentum (OAM). To further increase the data transmission rate, more degrees of freedom are required to form a densely packed mode space. Here we move beyond OAM and demonstrate multiplexing and demultiplexing using both the radial and azimuthal degrees of freedom. We achieve this with a holographic approach that allows over 100 modes to be encoded on a single hologram, across a wide wavelength range, in a wavelength independent manner. Our results offer a new tool that will prove useful in realizing higher bit rates for next generation optical networks.
Angular response of hot wire probes
di Mare, L.; Jelly, T. O.; Day, I. J.
2017-03-01
A new equation for the convective heat loss from the sensor of a hot-wire probe is derived which accounts for both the potential and the viscous parts of the flow past the prongs. The convective heat loss from the sensor is related to the far-field velocity by an expression containing a term representing the potential flow around the prongs, and a term representing their viscous effect. This latter term is absent in the response equations available in the literature but is essential in representing some features of the observed response of miniature hot-wire probes. The response equation contains only four parameters but it can reproduce, with great accuracy, the behaviour of commonly used single-wire probes. The response equation simplifies the calibration the angular response of rotated slanted hot-wire probes: only standard King’s law parameters and a Reynolds-dependent drag coefficient need to be determined.
Orbital angular momentum photonic quantum interface
Li, Yan; Ding, Dong-Sheng; Zhang, Wei; Shi, Shuai; Shi, Bao-Sen; Guo, Guang-Can
2014-01-01
High dimensional orbital angular momentum (OAM) light states are very important in enhancing the information carrying capacity in optical communications and quantum key distributions. Light at wavelengths of fiber communication windows or free space communication windows are suitable for long distance quantum communication, but most quantum processing tasks are performed in the visible wavelength ranges. The interface to bridge the wavelength gap of single photon with Gaussian shape has been realized, however, to create such interface for OAM-carrying light is a great challenge. We report the demonstration of such an interface to frequency up-conversion of herald single photon OAM state from 1560nm to 525nm with high efficiency by using nonlinear crystal in an external cavity. We show that different single photon OAM light shapes are observed directly by using single photon counting camera and the single photon entangled property is retained in the conversion process.
Sharepoint Extranet AngularJS:llä
2016-01-01
Tämä opinnäytetyö käsittelee Sharepoint-ratkaisua AngularJS-ohjelmistokehyksen avulla. Työn tarkoituksena oli toteuttaa uusi sivusto Sharepoint-dokumenttikirjastoja varten. Tämä työ tehtiin toimeksiantona Visualweb Oy:lle. Tavoitteena oli tehdä Sharepoint-sivusto, joka toimisi varsinaisen Sharepoint-palvelimen etusivuna ja käyttöliittymänä. Sivusto toimii asiakkaalla käyttöliittymänä dokumenttikirjastoon. Käyn työssä läpi ne teknologiat, joita projektissa käytettiin. Työssä esitellään A...
Coherent control of photoelectron wavepacket angular interferograms
Hockett, P.; Wollenhaupt, M.; Baumert, T.
2015-11-01
Coherent control over photoelectron wavepackets, via the use of polarization-shaped laser pulses, can be understood as a time and polarization-multiplexed process, where the final (time-integrated) observable coherently samples all instantaneous states of the light-matter interaction. In this work, we investigate this multiplexing via computation of the observable photoelectron angular interferograms resulting from multi-photon atomic ionization with polarization-shaped laser pulses. We consider the polarization sensitivity of both the instantaneous and cumulative continuum wavefunction; the nature of the coherent control over the resultant photoelectron interferogram is thus explored in detail. Based on this understanding, the use of coherent control with polarization-shaped pulses as a methodology for a highly multiplexed coherent quantum metrology is also investigated, and defined in terms of the information content of the observable.
Coherent Control of Photoelectron Wavepacket Angular Interferograms
Hockett, Paul; Baumert, Thomas
2015-01-01
Coherent control over photoelectron wavepackets, via the use of polarization-shaped laser pulses, can be understood as a time and polarization-multiplexed process. In this work, we investigate this multiplexing via computation of the observable photoelectron angular interferograms resulting from multi-photon atomic ionization with polarization-shaped laser pulses. We consider the polarization sensitivity of both the instantaneous and cumulative continuum wavefunction; the nature of the coherent control over the resultant photoelectron interferogram is thus explored in detail. Based on this understanding, the use of coherent control with polarization-shaped pulses as a methodology for a highly multiplexed coherent quantum metrology is also investigated, and defined in terms of the information content of the observable.
Angular momentum of dark matter black holes
Frampton, Paul H.
2017-04-01
We provide strongly suggestive evidence that the halo constituents of dark matter are Primordial Intermediate-Mass Black Holes (PIMBHs). PIMBHs are described by a Kerr metric with two parameters, mass M and angular momentum J. There has been little discussion of J since it plays no role in the upcoming attempt at PIMBH detection by microlensing. Nevertheless J does play a central role in understanding their previous lack of detection, especially by CMB distortion. We explain why bounds previously derived from lack of CMB distortion are too strong for PIMBHs with J non-vanishing and that, provided almost no dark matter black holes originate from stellar collapse, excessive CMB distortion is avoided.
Angular Spectrum Simulation of Pulsed Ultrasound Fields
DEFF Research Database (Denmark)
Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt
2009-01-01
The optimization of non-linear ultrasound imaging should in a first step be based on simulation, as this makes parameter studies considerably easier than making transducer prototypes. Such a simulation program should be capable of simulating non-linear pulsed fields for arbitrary transducer...... geometries for any kind of focusing and apodization. The Angular Spectrum Approach (ASA) is capable of simulating monochromatic non-linear acoustic wave propagation. However, for ultrasound imaging the time response of each specific point in space is required, and a pulsed ASA simulation with multi temporal....... The RMS error of the pulses for all points in the simulated plane is 10.9%. The good agreement between ASA and Field II simulation for the pulsed ultrasound fields obtained in this paper makes it possible to expand Field II to non-linear pulsed fields....
Effects of Angular Momentum on Halo Profiles
Lentz, Erik W; Rosenberg, Leslie J
2016-01-01
The near universality of DM halo density profiles provided by N-body simulations has proven to be robust against changes in total mass density, power spectrum, and some forms of initial velocity dispersion. In this letter we study the effects of coherently spinning up an isolated DM-only progenitor on halo structure. Halos with spins within several standard deviations of the simulated mean ($\\lambda \\lesssim 0.20$) produce profiles with negligible deviations from the universal form. Only when the spin becomes quite large ($\\lambda \\gtrsim 0.20$) do departures become evident. The angular momentum distribution also exhibits a near universal form, which is also independent of halo spin up to $\\lambda \\lesssim 0.20$. A correlation between these epidemic profiles and the presence of a strong bar in the virialized halo is also observed. These bar structures bear resemblance to the radial orbit instability in the rotationless limit.
High Orbital Angular Momentum Harmonic Generation
Vieira, J.; Trines, R. M. G. M.; Alves, E. P.; Fonseca, R. A.; Mendonça, J. T.; Bingham, R.; Norreys, P.; Silva, L. O.
2016-12-01
We identify and explore a high orbital angular momentum (OAM) harmonics generation and amplification mechanism that manipulates the OAM independently of any other laser property, by preserving the initial laser wavelength, through stimulated Raman backscattering in a plasma. The high OAM harmonics spectra can extend at least up to the limiting value imposed by the paraxial approximation. We show with theory and particle-in-cell simulations that the orders of the OAM harmonics can be tuned according to a selection rule that depends on the initial OAM of the interacting waves. We illustrate the high OAM harmonics generation in a plasma using several examples including the generation of prime OAM harmonics. The process can also be realized in any nonlinear optical Kerr media supporting three-wave interactions.
The Angular Trispectrum of the CMB
Hu, W
2001-01-01
We study the general properties of the CMB temperature four-point function, specifically its harmonic analogue the angular trispectrum, and illustrate its utility in finding optimal quadratic statistics through the weak gravitational lensing effect. We determine the general form of the trispectrum, under the assumptions of rotational, permutation, and parity invariance, its estimators on the sky, and their Gaussian noise properties. The signal-to-noise in the trispectrum can be highly configuration dependent and any quadratic statistic used to compress the information to a manageable two-point level must be carefully chosen. Through a systematic study, we determine that for the case of lensing a specific statistic, the divergence of a filtered temperature-weighted temperature-gradient map, contains the maximal signal-to-noise and reduces the variance of estimates of the large-scale convergence power spectrum by over an order of magnitude over previous gradient-gradient techniques. The total signal-to-noise fo...
Moon influence on equatorial atmospheric angular momentum
Bizouard, Christian; Zotov, Leonid; Sidorenkov, Nikolay
2014-05-01
The variation of the equatorial atmospheric angular momentum function, coordinated with respect to a star-fixed system, is investigated in relation with the lunar tide. We isolate the rapid fluctuations, below 30 days, where Moon motion has a possible influence. First we notice that pressure term and wind term are almost proportional, by contrast to celestial seasonal band (S1). This would mean that, in this frequency band, the torque of the atmosphere on the solid Earth mostly results from the equatorial bulge. Spectrum reveals sharp lunar tidal peaks at 13.66 days (O1 diurnal tide in the terrestrial frame) and 13.63 days, reflecting the Moon influence on meridional circulation. We also observe powerful episodic fluctuations between 5 and 8 days (up to 10 mas), possibly resulting from non linear effect of the O1 tide, or tidal waves 2Q1 (6.86 days) and σ1 (7.095 days).
Orbital angular momentum-entanglement frequency transducer
Zhou, Zhi-Yuan; Li, Yan; Ding, Dong-Sheng; Zhang, Wei; Shi, Shuai; Dong, Ming-Xin; Shi, Bao-Sen; Guo, Guang-Can
2016-01-01
Entanglement is a vital resource for realizing many tasks such as teleportation, secure key distribution, metrology and quantum computations. To effectively build entanglement between different quantum systems and share information between them, a frequency transducer to convert between quantum states of different wavelengths while retaining its quantum features is indispensable. Information encoded in the photons orbital angular momentum OAM degrees of freedom is preferred in harnessing the information carrying capacity of a single photon because of its unlimited dimensions. A quantum transducer, which operates at wavelengths from 1558.3 nm to 525 nm for OAM qubits, OAMpolarization hybrid entangled states, and OAM entangled states, is reported for the first time. Nonclassical properties and entanglements are demonstrated following the conversion process by performing quantum tomography, interference, and Bell inequality measurements. Our results demonstrate the capability to create an entanglement link betwe...
Nuclear scissors modes and hidden angular momenta
Balbutsev, E B; Schuck, P
2016-01-01
The coupled dynamics of low lying modes and various giant resonances are studied with the help of the Wigner Function Moments method generalized to take into account spin degrees of freedom and pair correlations simultaneously. The method is based on Time Dependent Hartree-Fock-Bogoliubov equations. The model of the harmonic oscillator including spin-orbit potential plus quadrupole-quadrupole and spin-spin interactions is considered. New low lying spin dependent modes are analyzed. Special attention is paid to the scissors modes. A new source of nuclear magnetism, connected with counter-rotation of spins up and down around the symmetry axis (hidden angular momenta), is discovered. Its inclusion into the theory allows one to improve substantially the agreement with experimental data in the description of energies and transition probabilities of scissors modes.
IDENTIFIKASI MIKROORGANISE STAPHYLOCOCCUS AUREUS PADA PENDERITA ANGULAR CHEILITIS
MINARTI, NURHAERATUL
2012-01-01
2011 Pada suatu penelitian tentang Angular cheilitis ditemukan Staphylococcus aureus hampir dua kali dari candida albicans. Oleh karena itu tujuan penelitian ini adalah untuk mengidentifikasi pengaruh Staphylococcus aureus pada penyakit Angular cheilitis. Sampel penelitian adalah 30 pasien yang datang ke Rumah Sakit Gigi dan Mulut Halimah Daeng Sikati Kandea Bagian Penyakit Gigi dan Mulut dalam periode waktu bulan Oktober-November 2011. Apusan pada permukaan lesi angular cheilitis dima...
Ideal linear-chain polymers with fixed angular momentum.
Brunner, Matthew; Deutsch, J M
2011-07-01
The statistical mechanics of a linear noninteracting polymer chain with a large number of monomers is considered with fixed angular momentum. The radius of gyration for a linear polymer is derived exactly by functional integration. This result is then compared to simulations done with a large number of noninteracting rigid links at fixed angular momentum. The simulation agrees with the theory up to finite-size corrections. The simulations are also used to investigate the anisotropic nature of a spinning polymer. We find universal scaling of the polymer size along the direction of the angular momentum, as a function of rescaled angular momentum.
Whole-body angular momentum in incline and decline walking.
Silverman, Anne K; Wilken, Jason M; Sinitski, Emily H; Neptune, Richard R
2012-04-01
Angular momentum is highly regulated over the gait cycle and is important for maintaining dynamic stability and control of movement. However, little is known regarding how angular momentum is regulated on irregular surfaces, such as slopes, when the risk of falling is higher. This study examined the three-dimensional whole-body angular momentum patterns of 30 healthy subjects walking over a range of incline and decline angles. The range of angular momentum was either similar or reduced on decline surfaces and increased on incline surfaces relative to level ground, with the greatest differences occurring in the frontal and sagittal planes. These results suggest that angular momentum is more tightly controlled during decline walking when the risk of falling is greater. In the frontal plane, the range of angular momentum was strongly correlated with the peak hip and knee abduction moments in early stance. In the transverse plane, the strongest correlation occurred with the knee external rotation peak in late stance. In the sagittal plane, all external moment peaks were correlated with the range of angular momentum. The peak ankle plantarflexion, knee flexion and hip extension moments were also strongly correlated with the sagittal-plane angular momentum. These results highlight how able-bodied subjects control angular momentum differently on sloped surfaces relative to level walking and provide a baseline for comparison with pathological populations that are more susceptible to falling.
System Dynamics and Adaptive Control for MEMS Gyroscope Sensor
Juntao Fei; Hongfei Ding
2010-01-01
This paper presents an adaptive control approach for Micro-Electro-Mechanical Systems (MEMS) z-axis gyroscope sensor. The dynamical model of MEMS gyroscope sensor is derived and adaptive state tracking control for MEMS gyroscope is developed. The proposed adaptive control approaches can estimate the angular velocity and the damping and stiffness coefficients including the coupling terms due to the fabrication imperfection. The stability of the closed-loop systems is established with the propo...
System Dynamics and Adaptive Control for MEMS Gyroscope Sensor
Juntao Fei; Hongfei Ding
2011-01-01
This paper presents an adaptive control approach for Micro-Electro-Mechanical Systems (MEMS) z-axis gyroscope sensor. The dynamical model of MEMS gyroscope sensor is derived and adaptive state tracking control for MEMS gyroscope is developed. The proposed adaptive control approaches can estimate the angular velocity and the damping and stiffness coefficients including the coupling terms due to the fabrication imperfection. The stability of the closed-loop systems is established with the propo...
DEFF Research Database (Denmark)
Petersen, Kjell Yngve; Søndergaard, Karin; Kongshaug, Jesper
2015-01-01
Adaptive Lighting Adaptive lighting is based on a partial automation of the possibilities to adjust the colour tone and brightness levels of light in order to adapt to people’s needs and desires. IT support is key to the technical developments that afford adaptive control systems. The possibilities...... offered by adaptive lighting control are created by the ways that the system components, the network and data flow can be coordinated through software so that the dynamic variations are controlled in ways that meaningfully adapt according to people’s situations and design intentions. This book discusses...... differently into an architectural body. We also examine what might occur when light is dynamic and able to change colour, intensity and direction, and when it is adaptive and can be brought into interaction with its surroundings. In short, what happens to an architectural space when artificial lighting ceases...
3D printed bio-inspired angular acceleration sensor
Tiem, van Joël; Groenesteijn, Jarno; Sanders, Remco; Krijnen, Gijs
2015-01-01
We present a biomimetic angular acceleration sensor inspired by the vestibular system, as found e.g. in mammals and fish. The sensor consist of a fluid filled circular channel. When exposed to angular accelerations the fluid flows relative to the channel. Read-out is based on electromagnetic flow se
Learning web development with Bootstrap and AngularJS
Radford, Stephen
2015-01-01
Whether you know a little about Bootstrap or AngularJS, or you're a complete beginner, this book will enhance your capabilities in both frameworks and you'll build a fully functional web app. A working knowledge of HTML, CSS, and JavaScript is required to fully get to grips with Bootstrap and AngularJS.
Fundamental methods to measure the orbital angular momentum of light
Berkhout, Gregorius Cornelis Gerardus (Joris)
2011-01-01
Light is a ubiquitous carrier of information. This information can be encoded in the intensity, direction, frequency and polarisation of the light and, which was described more recently, in its orbital angular momentum. Although creating light beams with orbital angular momentum is relatively easy,
Angular Momentum Phase State Representation for Quantum Pendulum
Institute of Scientific and Technical Information of China (English)
FAN Hong-Yi; WANG Ji-Suo
2005-01-01
To consummate the quantum pendulum theory whose Hamiltonian takes bosonic operator formalism and manifestly exhibits its dynamic behaviour in the entangled state representation, we introduce angular momentum state representation and phase state representation. It turns out that the angular momentum state is the partial wave expansion of the entangled state.
Relativistic calculations of angular dependent photoemission time delay
Kheifets, A S; Deshmukh, P C; Dolmatov, V K; Manson, S T
2016-01-01
Angular dependence of photoemission time delay for the valence $np_{3/2}$ and $np_{1/2}$ subshells of Ar, Kr and Xe is studied in the dipole relativistic random phase approximation. Strong angular anisotropy of the time delay is reproduced near respective Cooper minima while the spin-orbit splitting affects the time delay near threshold.
Evolution equations for higher moments of angular momentum distributions
Hägler, P
1998-01-01
Based on a sumrule for the nucleon spin we expand quark and gluon orbital angular momentum operators and derive an evolution matrix for higher moments of the corresponding distributions. In combination with the spin-dependent DGLAP-matrix we find a complete set of spin and orbital angular momentum evolution equations.
Angular cheilitis occurring during orthodontic treatment: a case series.
Cross, David L; Short, Laura J
2008-12-01
Clinical experience has shown that angular cheilitis can occur during orthodontic treatment and may persist into retention, but the incidence of the condition is unknown. The purpose of this paper is to increase the awareness among clinicians of angular cheilitis occurring during orthodontic treatment. It also proposes a treatment regime which may be used.
Iron deficiency: an overlooked predisposing factor in angular cheilitis.
Murphy, N C; Bissada, N F
1979-10-01
Clinicians who recommend the use of antifungal agents for angular cheilitis may be treating the symptoms and not the predisposing cause of the disease. Iron deficiency should be considered as part of the differential diagnosis whenever angular cheilitis is encountered, especially in women of child-bearing age.
CLASS: The Cosmology Large Angular Scale Surveyor
Essinger-Hileman, Thomas; Amiri, Mandana; Appel, John W; Araujo, Derek; Bennett, Charles L; Boone, Fletcher; Chan, Manwei; Cho, Hsiao-Mei; Chuss, David T; Colazo, Felipe; Crowe, Erik; Denis, Kevin; Dünner, Rolando; Eimer, Joseph; Gothe, Dominik; Halpern, Mark; Harrington, Kathleen; Hilton, Gene; Hinshaw, Gary F; Huang, Caroline; Irwin, Kent; Jones, Glenn; Karakla, John; Kogut, Alan J; Larson, David; Limon, Michele; Lowry, Lindsay; Marriage, Tobias; Mehrle, Nicholas; Miller, Amber D; Miller, Nathan; Moseley, Samuel H; Novak, Giles; Reintsema, Carl; Rostem, Karwan; Stevenson, Thomas; Towner, Deborah; U-Yen, Kongpop; Wagner, Emily; Watts, Duncan; Wollack, Edward; Xu, Zhilei; Zeng, Lingzhen
2014-01-01
The Cosmology Large Angular Scale Surveyor (CLASS) is an experiment to measure the signature of a gravita-tional-wave background from inflation in the polarization of the cosmic microwave background (CMB). CLASS is a multi-frequency array of four telescopes operating from a high-altitude site in the Atacama Desert in Chile. CLASS will survey 70\\% of the sky in four frequency bands centered at 38, 93, 148, and 217 GHz, which are chosen to straddle the Galactic-foreground minimum while avoiding strong atmospheric emission lines. This broad frequency coverage ensures that CLASS can distinguish Galactic emission from the CMB. The sky fraction of the CLASS survey will allow the full shape of the primordial B-mode power spectrum to be characterized, including the signal from reionization at low $\\ell$. Its unique combination of large sky coverage, control of systematic errors, and high sensitivity will allow CLASS to measure or place upper limits on the tensor-to-scalar ratio at a level of $r=0.01$ and make a cosmi...
Tracing the Angular Dependence of the CGM
Nattinger, Michael; Christensen, Charlotte
2017-01-01
The circumgalactic media (CGM) is enriched with metals through a process called the baryon cycle, which may play a significant role in the regulation of star formation. While the relationship between the CGM’s baryonic makeup and impact parameter is well documented, the relationship between the baryonic distribution of the CGM and the azimuthal angle out of the plane of the galaxy remains an open question. We investigated the angular distribution of baryons in the CGM by creating mock-absorption line spectra for a high-resolution simulation of a Milky Way-like galaxy at redshift zero. By comparison with data from the Cosmic Origins Spectrograph-Halos survey, we determined that our equivalent widths of HI, MgII, CIII, SiII, and SiIII are consistent with observations. Using our data, we found that low ionization state material is more prevalent at low azimuthal angles and that high ionization state material is more prevalent at high angles within the virial radius. We attributed this increased ionization to higher temperatures at high angles. We also found that the highest metallicity levels appear at high and low azimuthal angles, with lower metallicities at middle angles. This evidence supports the recycled accretion model of CGM baryon flow.
Angular velocity and centripetal acceleration relationship
Monteiro, Martín; Cabeza, Cecilia; Marti, Arturo C.; Vogt, Patrik; Kuhn, Jochen
2014-05-01
During the last few years, the growing boom of smartphones has given rise to a considerable number of applications exploiting the functionality of the sensors incorporated in these devices. A sector that has unexpectedly taken advantage of the power of these tools is physics teaching, as reflected in several recent papers. In effect, the use of smartphones has been proposed in several physics experiments spanning mechanics, electromagnetism, optics, oscillations, and waves, among other subjects. Although mechanical experiments have received considerable attention, most of them are based on the use of the accelerometer. An aspect that has received less attention is the use of rotation sensors or gyroscopes. An additional advance in the use of these devices is given by the possibility of obtaining data using the accelerometer and the gyroscope simultaneously. The aim of this paper is to consider the relation between the centripetal acceleration and the angular velocity. Instead of using a formal laboratory setup, in this experiment a smartphone is attached to the floor of a merry-go-round, found in many playgrounds. Several experiments were performed with the roundabout rotating in both directions and with the smart-phone at different distances from the center. The coherence of the measurements is shown.
Cyclic transformation of orbital angular momentum modes
Schlederer, Florian; Krenn, Mario; Fickler, Robert; Malik, Mehul; Zeilinger, Anton
2016-04-01
The spatial modes of photons are one realization of a QuDit, a quantum system that is described in a D-dimensional Hilbert space. In order to perform quantum information tasks with QuDits, a general class of D-dimensional unitary transformations is needed. Among these, cyclic transformations are an important special case required in many high-dimensional quantum communication protocols. In this paper, we experimentally demonstrate a cyclic transformation in the high-dimensional space of photonic orbital angular momentum (OAM). Using simple linear optical components, we show a successful four-fold cyclic transformation of OAM modes. Interestingly, our experimental setup was found by a computer algorithm. In addition to the four-cyclic transformation, the algorithm also found extensions to higher-dimensional cycles in a hybrid space of OAM and polarization. Besides being useful for quantum cryptography with QuDits, cyclic transformations are key for the experimental production of high-dimensional maximally entangled Bell-states.
Axions and the Galactic Angular Momentum Distribution
Banik, N
2013-01-01
We analyze the behavior of axion dark matter before it falls into a galactic gravitational potential well. The axions thermalize sufficiently fast by gravitational self-interactions that almost all go to their lowest energy state consistent with the total angular momentum acquired from tidal torquing. That state is a state of rigid rotation on the turnaround sphere. It predicts the occurrence and detailed properties of the caustic rings of dark matter for which observational evidence had been found earlier. We show that the vortices in the axion Bose-Einstein condensate (BEC) are attractive, unlike those in superfluid $^4$He and dilute gases. We expect that a large fraction of the vortices in the axion BEC join into a single big vortex along the rotation axis of the galaxy. The resulting enhancement of caustic rings explains the typical size of the rises in the Milky Way rotation curve attributed to caustic rings. We show that baryons and ordinary cold dark matter particles are entrained by the axion BEC and ...
Orbital angular momentum divider of light
Dong, Hailong Zhou Jianji; Cai, Xinlun; Yu, SiYuan; Zhang, Xinliang
2016-01-01
Manipulation of orbital angular momentum (OAM) of light is essential in OAM-based optical systems. Especially, OAM divider, which can convert the incoming OAM mode into one or several new smaller modes in proportion at different spatial paths, is very useful in OAM-based optical networks. However, this useful tool was never reported yet. For the first time, we put forward a passive OAM divider based on coordinate transformation. The device consists of a Cartesian to log-polar coordinate converter and an inverse converter. The first converter converts the OAM light into a rectangular-shaped plane light with a transverse phase gradient. And the second converter converts the plane light into multiple diffracted light. The OAM of zeroth-order diffracted light is the product of the input OAM and the scaling parameter. The residual light is output from other diffracted orders. Furthermore, we extend the scheme to realize equal N-dividing of OAM and arbitrary dividing of OAM. The ability of dividing OAM shows huge p...
Millimetre Wave with Rotational Orbital Angular Momentum
Zhang, Chao; Ma, Lu
2016-09-01
Orbital angular momentum (OAM) has been widely studied in fibre and short-range communications. The implementation of millimetre waves with OAM is expected to increase the communication capacity. Most experiments demonstrate the distinction of OAM modes by receiving all of the energy in the surface vertical to the radiation axis in space. However, the reception of OAM is difficult in free space due to the non-zero beam angle and divergence of energy. The reception of OAM in the space domain in a manner similar to that in optical fibres (i.e., receiving all of the energy rings vertical to the radiation axis) is impractical, especially for long-distance transmission. Here, we fabricate a prototype of the antenna and demonstrate that rather than in the space domain, the OAM can be well received in the time domain via a single antenna by rotating the OAM wave at the transmitter, i.e., the radio wave with rotational OAM. The phase and frequency measured in the experiment reveal that for different OAM modes, the received signals act as a commonly used orthogonal frequency division multiplexing (OFDM) signal in the time domain. This phase rotation has promising prospects for use in the practical reception of different OAMs of millimetre waves in long-distance transmission.
Orbital Angular Momentum-Entanglement Frequency Transducer
Zhou, Zhi-Yuan; Liu, Shi-Long; Li, Yan; Ding, Dong-Sheng; Zhang, Wei; Shi, Shuai; Dong, Ming-Xin; Shi, Bao-Sen; Guo, Guang-Can
2016-09-01
Entanglement is a vital resource for realizing many tasks such as teleportation, secure key distribution, metrology, and quantum computations. To effectively build entanglement between different quantum systems and share information between them, a frequency transducer to convert between quantum states of different wavelengths while retaining its quantum features is indispensable. Information encoded in the photon's orbital angular momentum (OAM) degrees of freedom is preferred in harnessing the information-carrying capacity of a single photon because of its unlimited dimensions. A quantum transducer, which operates at wavelengths from 1558.3 to 525 nm for OAM qubits, OAM-polarization hybrid-entangled states, and OAM-entangled states, is reported for the first time. Nonclassical properties and entanglements are demonstrated following the conversion process by performing quantum tomography, interference, and Bell inequality measurements. Our results demonstrate the capability to create an entanglement link between different quantum systems operating in a photon's OAM degrees of freedom, which will be of great importance in building a high-capacity OAM quantum network.
Millimetre Wave with Rotational Orbital Angular Momentum
Zhang, Chao; Ma, Lu
2016-01-01
Orbital angular momentum (OAM) has been widely studied in fibre and short-range communications. The implementation of millimetre waves with OAM is expected to increase the communication capacity. Most experiments demonstrate the distinction of OAM modes by receiving all of the energy in the surface vertical to the radiation axis in space. However, the reception of OAM is difficult in free space due to the non-zero beam angle and divergence of energy. The reception of OAM in the space domain in a manner similar to that in optical fibres (i.e., receiving all of the energy rings vertical to the radiation axis) is impractical, especially for long-distance transmission. Here, we fabricate a prototype of the antenna and demonstrate that rather than in the space domain, the OAM can be well received in the time domain via a single antenna by rotating the OAM wave at the transmitter, i.e., the radio wave with rotational OAM. The phase and frequency measured in the experiment reveal that for different OAM modes, the received signals act as a commonly used orthogonal frequency division multiplexing (OFDM) signal in the time domain. This phase rotation has promising prospects for use in the practical reception of different OAMs of millimetre waves in long-distance transmission. PMID:27596746
Optical communications beyond orbital angular momentum
Rosales-Guzmán, Carmelo; Trichili, Abderrahmen; Dudley, Angela; Ndagano, Bienvenu; Ben Salem, Amine; Zghal, Mourad; Forbes, Andrew
2016-09-01
Current optical communication technologies are predicted to face a bandwidth capacity limit in the near future. The nature of the limitation is fundamental rather than technological and is set by nonlinearities in optical fibers. One solution, suggested over 30 years ago, comprises the use of spatial modes of light as information carriers. Along this direction, light beams endowed with orbital angular momentum (OAM) have been demonstrated as potential information carriers in both, free space and fibres. However, recent studies suggest that purely OAM modes does not increase the bandwidth of optical communication systems. In fact, in all work to date, only the azimuthal component of transverse spatial modes has been used. Crucially, all transverse spatial modes require two degrees of freedom to be described; in the context of Laguerre-Gaussian (LGp`) beams these are azimuthal (l) and radial (p), the former responsible for OAM. Here, we demonstrate a technique where both degrees of freedom of LG modes are used as information carrier over free space. We transfer images encoded using 100 spatial modes in three wavelengths as our basis, and employ a spatial demultiplexing scheme that detects all 100 modes simultaneously. Our scheme is a hybrid of MIMO and SMM, and serves as a proof-of-principle demonstration. The cross-talk between the modes is small and independent of whether OAM modes are used or not.
Extraordinary photons with unusual angular momentum
Institute of Scientific and Technical Information of China (English)
YAO ZhiXin; ZHONG JianWei; MAO BangNing; PAN BaiLiang
2009-01-01
A series of novel state-vector functions (SVFs), which is the general solution of the Schrodinger equation for a photon, are constructed. Each set of these functions consists of a triplet of eigen-SVFs: The triplet can be broken down into a pair of nonzero/-order functions and a single zero-order function. The photons, described with a triplet of eigen-SVFs, possess all the quantum characteristics of a photon: In addition to common attributes like energy E=hω, and momentum Pz= hk; they also exhibit different angular momenta (AM) Lz+=Ih, Lz-= Ih, and Lz0=0, where I≥1. In other words, in addition to usual eigenvalues Lz±=±h, there are unusual nonzero/-order eigenvalues Lz±=±Ih and a zero-order eigenvalue Lz0 =0 for AM of a photon. By a series of SVFs, the pattern from nonzero /-order and zero-order Laguerre-Gaussian modes of a laser beam is explained well from a quantum mechanical point of view.
Extraordinary photons with unusual angular momentum
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
A series of novel state-vector functions (SVFs), which is the general solution of the Schrdinger equa- tion for a photon, are constructed. Each set of these functions consists of a triplet of eigen-SVFs: The triplet can be broken down into a pair of nonzero l-order functions and a single zero-order function. The photons, described with a triplet of eigen-SVFs, possess all the quantum characteristics of a photon: In addition to common attributes like energy E = hω, and momentum pz = hκ, they also exhibit different angular momenta (AM) Lz+ = lh, Lz- = lh, and Lz0 = 0, where l≥1. In other words, in addition to usual ei- genvalues Lz±= ±h, there are unusual nonzero l-order eigenvalues Lz±= ±lh and a zero-order eigenvalue Lz0 = 0 for AM of a photon. By a series of SVFs, the pattern from nonzero l-order and zero-order La- guerre-Gaussian modes of a laser beam is explained well from a quantum mechanical point of view.
Cyclic transformation of orbital angular momentum modes
Schlederer, Florian; Fickler, Robert; Malik, Mehul; Zeilinger, Anton
2015-01-01
The spatial modes of photons are one realization of a QuDit, a quantum system that is described in a D-dimensional Hilbert space. In order to perform quantum information tasks with QuDits, a general class of D-dimensional unitary transformations is needed. Among these, cyclic transformations are an important special case required in many high-dimensional quantum communication protocols. In this paper, we experimentally demonstrate a cyclic transformation in the high-dimensional space of photonic orbital angular momentum (OAM). Using simple linear optical components, we show a successful four-fold cyclic transformation of OAM modes. Interestingly, our experimental setup was found by a computer algorithm. In addition to the four-cyclic transformation, the algorithm also found extensions to higher-dimensional cycles in a hybrid space of OAM and polarization. Besides being useful for quantum cryptography with QuDits, cyclic transformations are key for the experimental production of high-dimensional maximally enta...
CLASS: The Cosmology Large Angular Scale Surveyor
Essinger-Hileman, Thomas; Ali, Aamir; Amiri, Mandana; Appel, John W.; Araujo, Derek; Bennett, Charles L.; Boone, Fletcher; Chan, Manwei; Cho, Hsiao-Mei; Chuss, David T.; Colazo, Felipe; Crowe, Erik; Denis, Kevin; Dunner, Rolando; Eimer, Joseph; Gothe, Dominik; Halpern, Mark; Kogut, Alan J.; Miller, Nathan; Moseley, Samuel; Rostem, Karwan; Stevenson, Thomas; Towner, Deborah; U-Yen, Kongpop; Wollack, Edward
2014-01-01
The Cosmology Large Angular Scale Surveyor (CLASS) is an experiment to measure the signature of a gravitational wave background from inflation in the polarization of the cosmic microwave background (CMB). CLASS is a multi-frequency array of four telescopes operating from a high-altitude site in the Atacama Desert in Chile. CLASS will survey 70% of the sky in four frequency bands centered at 38, 93, 148, and 217 GHz, which are chosen to straddle the Galactic-foreground minimum while avoiding strong atmospheric emission lines. This broad frequency coverage ensures that CLASS can distinguish Galactic emission from the CMB. The sky fraction of the CLASS survey will allow the full shape of the primordial B-mode power spectrum to be characterized, including the signal from reionization at low-length. Its unique combination of large sky coverage, control of systematic errors, and high sensitivity will allow CLASS to measure or place upper limits on the tensor-to-scalar ratio at a level of r = 0:01 and make a cosmic-variance-limited measurement of the optical depth to the surface of last scattering, tau. (c) (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Non-gaussian CMBR angular power spectra
Magueijo, J
1995-01-01
In this paper we show how the prediction of CMBR angular power spectra C_l in non-Gaussian theories is affected by a cosmic covariance problem, that is (C_l,C_{l'}) correlations impart features on any observed C_l spectrum which are absent from the average C^l spectrum. Therefore the average spectrum is rendered a bad observational prediction, and two new prediction strategies, better adjusted to these theories, are proposed. In one we search for hidden random indices conditional to which the theory is released from the correlations. Contact with experiment can then be made in the form of the conditional power spectra plus the random index distribution. In another approach we apply to the problem a principal component analysis. We discuss the effect of correlations on the predictivity of non-Gaussian theories. We finish by showing how correlations may be crucial in delineating the borderline between predictions made by non-Gaussian and Gaussian theories. In fact, in some particular theories, correlations may ...
Nuclear Level Density with Non-zero Angular Momentum
Institute of Scientific and Technical Information of China (English)
A.N. Behkami; M. Gholami; M. Kildir; M. Soltani
2006-01-01
The statistical properties of interacting fermions have been studied for various angular momentum with the inclusion of pairing interaction. The dependence of the critical temperature on angular momentum for several nuclei,have been studied. The yrast energy as a function of angular momentum for 28 Si and 24Mg nuclei have been calculated up to 60.0 MeV of excitation energy. The computed limiting angular momenta are compared with the experimental results for 26Al produced by 12C + 14N reaction. The relevant nuclear level densities for non-zero angular momentum have been computed for 44Ti and l36Ba nuclei. The results are compared with their corresponding values obtained from the approximateformulas.
Towards optical intensity interferometry for high angular resolution stellar astrophysics
Nunez, Paul D
2012-01-01
Most neighboring stars are still detected as point sources and are beyond the angular resolution reach of current observatories. Methods to improve our understanding of stars at high angular resolution are investigated. Air Cherenkov telescopes (ACTs), primarily used for Gamma-ray astronomy, enable us to increase our understanding of the circumstellar environment of a particular system. When used as optical intensity interferometers, future ACT arrays will allow us to detect stars as extended objects and image their surfaces at high angular resolution. Optical stellar intensity interferometry (SII) with ACT arrays, composed of nearly 100 telescopes, will provide means to measure fundamental stellar parameters and also open the possibility of model-independent imaging. A data analysis algorithm is developed and permits the reconstruction of high angular resolution images from simulated SII data. The capabilities and limitations of future ACT arrays used for high angular resolution imaging are investigated via ...
Alignment of wave functions for angular momentum projection
Taniguchi, Yasutaka
2016-01-01
Angular momentum projection is used to obtain eigen states of angular momentum from general wave functions. Multi-configuration mixing calculation with angular momentum projection is an important microscopic method in nuclear physics. For accurate multi-configuration mixing calculation with angular momentum projection, concentrated distribution of $z$ components $K$ of angular momentum in the body-fixed frame ($K$-distribution) is favored. Orientation of wave functions strongly affects $K$-distribution. Minimization of variance of $\\hat{J}_z$ is proposed as an alignment method to obtain wave functions that have concentrated $K$-distribution. Benchmark calculations are performed for $\\alpha$-$^{24}$Mg cluster structure, triaxially superdeformed states in $^{40}$Ar, and Hartree-Fock states of some nuclei. The proposed alignment method is useful and works well for various wave functions to obtain concentrated $K$-distribution.
Quantum hyper-entanglement and angular spectrum decomposition applied to sensors
Smith, James F.
2016-05-01
Hyper-entanglement with an emphasis on mode type is used to extend a previously developed atmospheric imaging system. Angular spectrum expansions combined with second quantization formalism permits many different mode types to be considered using a common formalism. Fundamental Gaussian, standard Hermite-Gaussian, standard Laguerre- Gaussian, and Bessel modes are developed. Hyper-entanglement refers to entanglement in more than one degree of freedom, e.g. polarization, energy-time and orbital angular momentum. The system functions at optical or infrared frequencies. Only the signal photon propagates in the atmosphere, the ancilla photon is retained within the detector. This results in loss being essentially classical, giving rise to stronger forms of entanglement. A simple atomic physics based model of the scattering target is developed. This model permits the derivation in closed form of the loss coefficient for photons with a given mode type scattering from the target. Signal loss models for propagation, transmission, detection, and scattering are developed and applied. The probability of detection of photonic orbital angular momentum is considered in terms of random media theory. A model of generation and detection efficiencies for the different degrees of freedom is also considered. The implications of loss mechanisms for signal to noise ratio (SNR), and other quantum information theoretic quantities are discussed. Techniques for further enhancing the system's SNR and resolution through adaptive optics are examined. The formalism permits random noise and entangled or nonentangled sources of interference to be modeled.
Angular Distribution and Angular Dispersion in Collision of 19F+27A1 at 114 MeV
Institute of Scientific and Technical Information of China (English)
WANG Qi; Li Zhi-Chang; LU Xiu-Qin; ZHAO Kui; LIU Jian-Cheng; SERGEY Yu-Kun; DONG Yu-Chuan; LI Song-Lin; DUAN Li-Min; XU Hu-Shan; XU Hua-Gen; CHEN Ruo-Fu; WU He-Yu; HAN Jian-Long
2004-01-01
Angular distributions of fragments B, C, N, O, F, Ne, Na, Mg and Al induced by the collision of 19F+27 A1 at 114MeV have been measured. Angular dispersion parameters are extracted from the experimental data and compared with the theoretical ones. The dynamic dispersions for dissipative products depend strongly on the charge number Z of the fragments.
Cepheids at high angular resolution: circumstellar envelope and pulsation
Gallenne, Alexandre
2011-12-01
In 2005, interferometric observations with VLTI/VINCI and CHARA/FLUOR revealed the existence of a circumstellar envelope (CSE) around some Cepheids. This surrounding material is particularly interesting for two reasons: it could have an impact on the distance estimates and could be linked to a past or on-going mass loss. The use of Baade-Wesselink methods for independent distance determinations could be significantly biased by the presence of these envelopes. Although their observations are difficult because of the high contrast between the photosphere of the star and the CSE, several observation techniques have the potential to improve our knowledge about their physical properties. In this thesis, I discuss in particular high angular resolution techniques that I applied to the study of several bright Galactic Cepheids. First, I used adaptive optic observations with NACO of the Cepheid RS Puppis, in order to deduce the flux ratio between the CSE and the photosphere of the star. In addition, I could carry out a statistical study of the speckle noise and inspect a possible asymmetry. Secondly, I analysed VISIR data to study the spectral energy distribution of a sample of Cepheids. These diffraction-limited images enabled me to carry out an accurate photometry in the N band and to detect an IR excess linked to the presence of a circumstellar component. On the other hand, applying a Fourier analysis I showed that some components are resolved. I then explored the K' band with the recombination instrument FLUOR for some bright Cepheids. Thanks to new set of data of Y Oph, I improved the study of its circumstellar envelope, using a ring-like model for the CSE. For two other Cepheids, U Vul and S Sge, I applied the interferometric Baade-Wesselink method in order to estimate their distance.
National Aeronautics and Space Administration — Advanced Diagnostics and Prognostics Testbed (ADAPT) Project Lead: Scott Poll Subject Fault diagnosis in electrical power systems Description The Advanced...
Angular dependent light emission from planar waveguides
Energy Technology Data Exchange (ETDEWEB)
Peter, Jaison, E-mail: jaison.peter@gmail.com [International School of Photonics, Cochin University of Science and Technology, Cochin 682022 (India); CRE" +E, IDEAS Research Institute, Robert Gordon University, Aberdeen AB10 7GJ (United Kingdom); Prabhu, Radhakrishna [CRE" +E, IDEAS Research Institute, Robert Gordon University, Aberdeen AB10 7GJ (United Kingdom); Radhakrishnan, P.; Vallabhan, C. P. G.; Nampoori, V. P. N.; Kailasnath, M. [International School of Photonics, Cochin University of Science and Technology, Cochin 682022 (India)
2015-01-07
We have investigated the angular dependence of amplified spontaneous emission (ASE) and laser emission from an asymmetric and free-standing polymer thin films doped with rhodamine 6G, which is transversely pumped by a pulsed Nd:YAG laser. A semi-leaky waveguide or quasi-waveguide structure has been developed by spin coating technique. In these waveguides, the light was confined by the film/air-film/glass substrate interfaces. At the film/substrate interface, a portion of light will reflect back into the film (guided mode) and the remaining refracted to the substrate resulting in cutoff modes. A blue-shift in ASE has been observed when the pump power was increased from 8 to 20 mW allowing a limited range of tuning of emission wavelength. To study the directionality of the ASE from the waveguide, we have measured the output intensity and FWHM of emission spectra as a function of viewing angle (θ) from the plane parallel to film. From the detailed examination of the output emission spectra, as +θ increases from 0° there has been an initial decrease in output intensity, but at a particular angle ≈10° an increase in output intensity was observed. This additional peak in output intensity as +θ is a clear indication of coexistence of the cutoff mode. We also present a compact solid-state laser based on leaky mode propagation from the dye-doped polymer free-standing film (∼50 μm thickness) waveguide. The partial reflections from the broad lateral surfaces of the free-standing films provided the optical feedback for the laser emission with high directionality. For a pump power of 22 mW, an intense line with FWHM <0.2 nm was observed at 578 nm.
The origin of angular momentum in dark matter halos
Vitvitska, M; Kravtsov, A V; Bullock, J S; Wechsler, R H; Primack, Joel R
2002-01-01
We propose a new explanation for the origin of angular momentum in galaxies and their dark halos, in which the halos obtain their spin through the cumulative acquisition of angular momentum from satellite accretion. In our model, the build-up of angular momentum is a random walk process associated with the mass assembly history of the halo's major progenitor. We assume no correlation between the angular momenta of accreted objects. Using the extended Press-Schechter approximation, we calculate the growth of mass, angular momentum, and spin parameter $\\lambda$ for many halos. Our random walk model reproduces the key features of the angular momentum of halos found in N-body simulations: a lognormal distribution in $\\lambda$ with an average of $ \\approx 0.04$, independent of mass and redshift. The evolution of the spin parameter in individual halos in this model is quite different from the steady increase with time of angular momentum in the tidal torque picture. We find both in N-body simulations and in our ran...
Knee abduction angular impulses during prolonged running with wedged insoles.
Lewinson, Ryan T; Worobets, Jay T; Stefanyshyn, Darren J
2013-07-01
Wedged insoles may produce immediate effects on knee abduction angular impulses during running; however, it is currently not known whether these knee abduction angular impulse magnitudes are maintained throughout a run when fatigue sets in. If changes occur, this could affect the clinical utility of wedged insoles in treating conditions such as patellofemoral pain. Thus, the purpose of this study was to determine whether knee abduction angular impulses are altered during a prolonged run with wedged insoles. It was hypothesized that knee abduction angular impulses would be reduced following a prolonged run with wedged insoles. Nine healthy runners participated. Runners were randomly assigned to either a 6-mm medial wedge condition or a 6-mm lateral wedge condition and then ran continuously overground for 30 min. Knee abduction angular impulses were quantified at 0 and 30 min using a gait analysis procedure. After 2 days, participants returned to perform the same test but with the other wedge type. Two-way repeated-measures analysis of variance was used to evaluate main effects of wedge condition and time and interactions between wedge condition and time (α = 0.05). Paired t-tests were used for post hoc analysis (α = 0.01). No interaction effects (p = 0.958) were found, and knee abduction angular impulses were not significantly different over time (p = 0.384). Lateral wedge conditions produced lesser knee abduction angular impulses than medial conditions at 0 min (difference of 2.79 N m s, p = 0.006) and at 30 min (difference of 2.76 N m s, p < 0.001). It is concluded that significant knee abduction angular impulse changes within wedge conditions do not occur during a 30-min run. Additionally, knee abduction angular impulse differences between wedge conditions are maintained during a 30-min run.
Coherent detection of orbital angular momentum in radio
Daldorff, L K S; Bergman, J E S; Isham, B; Al-Nuaimi, M K T; Forozesh, K; Carozzi, T D
2015-01-01
The angular momentum propagated by a beam of radiation has two contributions: spin angular momentum (SAM) and orbital angular momentum (OAM). SAM corresponds to wave polarisation, while OAM-carrying beams are characterized by a phase which is a function of azimuth. We demonstrate experimentally that radio beams propagating OAM can be generated and coherently detected using ordinary electric dipole antennas. The results presented here could pave the way for novel radio OAM applications in technology and science, including radio communication, passive remote sensing, and new types of active (continuous or pulsed transmission) electromagnetic measurements.
On Angular Sampling Methods for 3-D Spatial Channel Models
DEFF Research Database (Denmark)
Fan, Wei; Jämsä, Tommi; Nielsen, Jesper Ødum
2015-01-01
This paper discusses generating three dimensional (3D) spatial channel models with emphasis on the angular sampling methods. Three angular sampling methods, i.e. modified uniform power sampling, modified uniform angular sampling, and random pairing methods are proposed and investigated in detail....... The random pairing method, which uses only twenty sinusoids in the ray-based model for generating the channels, presents good results if the spatial channel cluster is with a small elevation angle spread. For spatial clusters with large elevation angle spreads, however, the random pairing method would fail...... and the other two methods should be considered....
Angular and radial mode analyzer for optical beams.
Abouraddy, Ayman F; Yarnall, Timothy M; Saleh, Bahaa E A
2011-12-01
We describe an approach to determining both the angular and the radial modal content of a scalar optical beam in terms of optical angular momentum modes. A modified Mach-Zehnder interferometer that incorporates a spatial rotator to determine the angular modes and an optical realization of the fractional Hankel transform (fHT) to determine the radial modes is analyzed. Varying the rotation angle and the order of the fHT produces a two-dimensional (2D) interferogram from which we extract the modal coefficients by simple 2D Fourier analysis.
Control of Angular Intervals for Angle-Multiplexed Holographic Memory
Kinoshita, Nobuhiro; Muroi, Tetsuhiko; Ishii, Norihiko; Kamijo, Koji; Shimidzu, Naoki
2009-03-01
In angle-multiplexed holographic memory, the full width at half maximum of the Bragg selectivity curves is dependent on the angle formed between the medium and incident laser beams. This indicates the possibility of high density and high multiplexing number by varying the angular intervals between adjacent holograms. We propose an angular interval scheduling for closely stacking holograms into medium even when the angle range is limited. We obtained bit error rates of the order of 10-4 under the following conditions: medium thickness of 1 mm, laser beam wavelength of 532 nm, and angular multiplexing number of 300.
Angular magnetoresistance in semiconducting undoped amorphous carbon thin films
Energy Technology Data Exchange (ETDEWEB)
Sagar, Rizwan Ur Rehman; Saleemi, Awais Siddique; Zhang, Xiaozhong, E-mail: xzzhang@tsinghua.edu.cn [Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, People' s Republic of China and Beijing National Center for Electron Microscopy, Beijing 100084 (China)
2015-05-07
Thin films of undoped amorphous carbon thin film were fabricated by using Chemical Vapor Deposition and their structure was investigated by using High Resolution Transmission Electron Microscopy and Raman Spectroscopy. Angular magnetoresistance (MR) has been observed for the first time in these undoped amorphous carbon thin films in temperature range of 2 ∼ 40 K. The maximum magnitude of angular MR was in the range of 9.5% ∼ 1.5% in 2 ∼ 40 K. The origin of this angular MR was also discussed.
Induced Compression of White Dwarfs by Angular Momentum Loss
Boshkayev, Kuantay; Ruffini, Remo; Zhami, Bakytzhan
2016-01-01
We investigate isolated sub- and super-Chandrasekhar white dwarfs which lose angular momentum through magnetic dipole braking. We construct constant rest mass sequences by fulfilling all stability criteria of rotating configurations and show how the main structure of white dwarfs such as the central density, mean radius and angular velocity change with time. We explicitly demonstrate that all isolated white dwarfs regardless of their masses, by angular momentum loss, shrink and increase their central density. We also analyze the effects of the structure parameters on the evolution timescale both in the case of constant magnetic field and constant magnetic flux.
Electro-optic analyzer of angular momentum hyperentanglement.
Wu, Ziwen; Chen, Lixiang
2016-02-25
Characterizing a high-dimensional entanglement is fundamental in quantum information applications. Here, we propose a theoretical scheme to analyze and characterize the angular momentum hyperentanglement that two photons are entangled simultaneously in spin and orbital angular momentum. Based on the electro-optic sampling with a proposed hyper-entanglement analyzer and the simple matrix operation using Cramer rule, our simulations show that it is possible to retrieve effectively both the information about the degree of polarization entanglement and the spiral spectrum of high-dimensional orbital angular momentum entanglement.
Detection of a spinning object using light's orbital angular momentum.
Lavery, Martin P J; Speirits, Fiona C; Barnett, Stephen M; Padgett, Miles J
2013-08-01
The linear Doppler shift is widely used to infer the velocity of approaching objects, but this shift does not detect rotation. By analyzing the orbital angular momentum of the light scattered from a spinning object, we observed a frequency shift proportional to product of the rotation frequency of the object and the orbital angular momentum of the light. This rotational frequency shift was still present when the angular momentum vector was parallel to the observation direction. The multiplicative enhancement of the frequency shift may have applications for the remote detection of rotating bodies in both terrestrial and astronomical settings.
Generation and detection of orbital angular momentum via metasurface.
Jin, Jinjin; Luo, Jun; Zhang, Xiaohu; Gao, Hui; Li, Xiong; Pu, Mingbo; Gao, Ping; Zhao, Zeyu; Luo, Xiangang
2016-04-07
Beams carrying orbital angular momentum possess a significant potential for modern optical technologies ranging from classical and quantum communication to optical manipulation. In this paper, we theoretically design and experimentally demonstrate an ultracompact array of elliptical nanoholes, which could convert the circularly polarized light into the cross-polarized vortex beam. To measure the topological charges of orbital angular momentum in a simple manner, another elliptical nanoholes array is designed to generate reference beam as a reference light. This approach may provide a new way for the generation and detection of orbital angular momentum in a compact device.
LCD-based digital eyeglass for modulating spatial-angular information.
Bian, Zichao; Liao, Jun; Guo, Kaikai; Heng, Xin; Zheng, Guoan
2015-05-04
Using programmable aperture to modulate spatial-angular information of light field is well-known in computational photography and microscopy. Inspired by this concept, we report a digital eyeglass design that adaptively modulates light field entering human eyes. The main hardware includes a transparent liquid crystal display (LCD) and a mini-camera. The device analyzes the spatial-angular information of the camera image in real time and subsequently sends a command to form a certain pattern on the LCD. We show that, the eyeglass prototype can adaptively reduce light transmission from bright sources by ~80% and retain transparency to other dim objects meanwhile. One application of the reported device is to reduce discomforting glare caused by vehicle headlamps. To this end, we report the preliminary result of using the reported device in a road test. The reported device may also find applications in military operations (sniper scope), laser counter measure, STEM education, and enhancing visual contrast for visually impaired patients and elderly people with low vision.
Lenoir, Matthieu; Musch, Eliane; Thiery, Evert; Savelsbergh, Geert J P
2002-12-01
The authors ran 3 experiments to investigate how catchers deal with the horizontal component of the ball's trajectory in an interception task during locomotion. The experiments were built upon the finding that velocity adaptations are based upon changes in the horizontal angular position or velocity of the ball with respect to the observer (M. Lenoir, M. Janssens, E. Musch, E. Thiery, J. Uyttenhove, 1999) a potential underlying information source for that strategy is described. In Experiment 1, actor (N = 10 participants)and ball approached each other along the legs of a V-shaped track. When the velocity and the initial angular bearing of the ball were varied, the observed behavior fitted with nulling the horizontal angular velocity of the ball: A positive or negative angular velocity was compensated by a velocity change. Evidence was obtained that those adaptations are modulated by a critical change in, rather than by a critical state of, the environment-actor system. In Experiment 2, the distance between the head and an artificial end-effector was varied. Irrespective of that distance, participants (N = 7) accelerated and decelerated in order to keep the angular velocity of the ball with respect to the end-effector close to constant. The ecological relevance of that constant bearing angle strategy was confirmed in Experiment 3: Participants (N = 7) in that experiment freely ran to catch fly balls. The present results support the concept that one can explain with a limited number of control variables an actor's behavior in an interception task during self-motion.
Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development
Chuss, D T; Amiri, M; Appel, J; Bennett, C L; Colazo, F; Denis, K L; Dünner, R; Essinger-Hileman, T; Eimer, J; Fluxa, P; Gothe, D; Halpern, M; Harrington, K; Hilton, G; Hinshaw, G; Hubmayr, J; Iuliano, J; Marriage, T A; Miller, N; Moseley, S H; Mumby, G; Petroff, M; Reintsema, C; Rostem, K; U-Yen, K; Watts, D; Wagner, E; Wollack, E J; Xu, Z; Zeng, L
2015-01-01
The Cosmology Large Angular Scale Surveyor (CLASS) will measure the polarization of the Cosmic Microwave Background to search for and characterize the polarized signature of inflation. CLASS will operate from the Atacama Desert and observe $\\sim$70% of the sky. A variable-delay polarization modulator (VPM) modulates the polarization at $\\sim$10 Hz to suppress the 1/f noise of the atmosphere and enable the measurement of the large angular scale polarization modes. The measurement of the inflationary signal across angular scales that span both the recombination and reionization features allows a test of the predicted shape of the polarized angular power spectra in addition to a measurement of the energy scale of inflation. CLASS is an array of telescopes covering frequencies of 38, 93, 148, and 217 GHz. These frequencies straddle the foreground minimum and thus allow the extraction of foregrounds from the primordial signal. Each focal plane contains feedhorn-coupled transition-edge sensors that simultaneously d...
"Angle" Operator Conjugate to Photon's Intrinsic Angular Momentum
Institute of Scientific and Technical Information of China (English)
范洪义
2001-01-01
We find the correct "angle" operator conjugate to the intrinsic angular momentum of the photon by introducing a suitable representation which involves both left-handed and right-handed polarization photon operators.
General covariant conservative angular momentum as internal charges
Institute of Scientific and Technical Information of China (English)
赵德品
1996-01-01
The usual approach to internal conservative charges is used to obtain the conservation laws of angular-momentum in both Einstein gravity and gravitational anyons.The results are in complete agreement with those of references.
Imaging the Earth's Interior: the Angular Distribution of Terrestrial Neutrinos
Fields, Brian D
2004-01-01
Decays of radionuclides throughout the Earth's interior produce geothermal heat, but also are a source of antineutrinos. The (angle-integrated) geoneutrino flux places an integral constraint on the terrestrial radionuclide distribution. In this paper, we calculate the angular distribution of geoneutrinos, which opens a window on the differential radionuclide distribution. We develop the general formalism for the neutrino angular distribution, and we present the inverse transformation which recovers the terrestrial radioisotope distribution given a measurement of the neutrino angular distribution. Thus, geoneutrinos not only allow a means to image the Earth's interior, but offering a direct measure of the radioactive Earth, both (1) revealing the Earth's inner structure as probed by radionuclides, and (2) allowing for a complete determination of the radioactive heat generation as a function of radius. We present the geoneutrino angular distribution for the favored Earth model which has been used to calculate g...
Quantum optimal control of photoelectron spectra and angular distributions
Goetz, R Esteban; Santra, Robin; Koch, Christiane P
2016-01-01
Photoelectron spectra and photoelectron angular distributions obtained in photoionization reveal important information on e.g. charge transfer or hole coherence in the parent ion. Here we show that optimal control of the underlying quantum dynamics can be used to enhance desired features in the photoelectron spectra and angular distributions. To this end, we combine Krotov's method for optimal control theory with the time-dependent configuration interaction singles formalism and a splitting approach to calculate photoelectron spectra and angular distributions. The optimization target can account for specific desired properties in the photoelectron angular distribution alone, in the photoelectron spectrum, or in both. We demonstrate the method for hydrogen and then apply it to argon under strong XUV radiation, maximizing the difference of emission into the upper and lower hemispheres, in order to realize directed electron emission in the XUV regime.
Pluto Moons exhibit Orbital Angular Momentum Quantization per Mass
Directory of Open Access Journals (Sweden)
Potter F.
2012-10-01
Full Text Available The Pluto satellite system of the planet plus five moons is shown to obey the quan- tum celestial mechanics (QCM angular momentum per mass quantization condition predicted for any gravitationally bound system.
Uncertainty Relation between Angular Momentum and Angle Variable.
Roy, C. L.; Sannigrahi, A. B.
1979-01-01
Discusses certain pitfalls regarding the uncertainty relation between angular momentum and the angle variable from a pedagogic point of view. Further, an uncertainty relation has been derived for these variables in a simple and consistant manner. (Author/HM)
Effect of angular momentum conservation on hydrodynamic simulations of colloids.
Yang, Mingcheng; Theers, Mario; Hu, Jinglei; Gompper, Gerhard; Winkler, Roland G; Ripoll, Marisol
2015-07-01
In contrast to most real fluids, angular momentum is not a locally conserved quantity in some mesoscopic simulation methods. Here we quantify the importance of this conservation in the flow fields associated with different colloidal systems. The flow field is analytically calculated with and without angular momentum conservation for the multiparticle collision dynamics (MPC) method, and simulations are performed to verify the predictions. The flow field generated around a colloidal particle moving under an external force with slip boundary conditions depends on the conservation of angular momentum, and the amplitude of the friction force is substantially affected. Interestingly, no dependence on the angular momentum conservation is found for the flow fields generated around colloids under the influence of phoretic forces. Moreover, circular Couette flow between a no-slip and a slip cylinder is investigated, which allows us to validate one of the two existing expressions for the MPC stress tensor.
Relevance of angular momentum conservation in mesoscale hydrodynamics simulations.
Götze, Ingo O; Noguchi, Hiroshi; Gompper, Gerhard
2007-10-01
The angular momentum is conserved in fluids with a few exceptions such as ferrofluids. However, it can be violated locally in fluid simulations to reduce computational costs. The effects of this violation are investigated using a particle-based simulation method, multiparticle collision dynamics, which can switch on or off angular-momentum conservation. To this end, we study circular Couette flows between concentric and eccentric cylinders, where nonphysical torques due to the lack of the angular-momentum conservation are found whereas the velocity field is not affected. In addition, in simulations of fluids with different viscosities in contact and star polymers in solvent, incorrect angular velocities occur. These results quantitatively agree with the theoretical predictions based on the macroscopic stress tensor.
Design and Implementation of a Digital Angular Rate Sensor
Directory of Open Access Journals (Sweden)
Zhen Peng
2010-10-01
Full Text Available With the aim of detecting the attitude of a rotating carrier, the paper presents a novel, digital angular rate sensor. The sensor consists of micro-sensing elements (gyroscope and accelerometer, signal processing circuit and micro-processor (DSP2812. The sensor has the feature of detecting three angular rates of a rotating carrier at the same time. The key techniques of the sensor, including sensing construction, sensing principles, and signal processing circuit design are presented. The test results show that the sensor can sense rolling, pitch and yaw angular rate at the same time and the measurement error of yaw (or pitch angular rate and rolling rate of the rotating carrier is less than 0.5%.
Design and implementation of a digital angular rate sensor.
Wu, Li-Feng; Peng, Zhen; Zhang, Fu-Xue
2010-01-01
With the aim of detecting the attitude of a rotating carrier, the paper presents a novel, digital angular rate sensor. The sensor consists of micro-sensing elements (gyroscope and accelerometer), signal processing circuit and micro-processor (DSP2812). The sensor has the feature of detecting three angular rates of a rotating carrier at the same time. The key techniques of the sensor, including sensing construction, sensing principles, and signal processing circuit design are presented. The test results show that the sensor can sense rolling, pitch and yaw angular rate at the same time and the measurement error of yaw (or pitch) angular rate and rolling rate of the rotating carrier is less than 0.5%.
Coriolis effects are principally caused by gyroscopic angular acceleration.
Isu, N; Yanagihara, M; Mikuni, T; Koo, J
1994-07-01
A cause of nausea evoked by cross-coupled rotation (termed Coriolis stimulus) was determined. Subjects were provided with two types of cross-coupled rotations: neck-forward flexion (Neck Flx) and upper body-forward flexion (Body Flx) during horizontal whole body rotation at a constant angular velocity. These Coriolis stimuli were given alternatively in an experimental sequence, and the severity of the nausea they evoked was compared by the subjects. The results indicated that the same quality of nausea was evoked by a slightly higher angular velocity during Body Flx (100.5 degrees/s) than during Neck Flx (90 degrees/s). While Body Flx generated Coriolis linear acceleration several times larger than Neck Flx, both the stimuli generated a similar magnitude of gyroscopic angular acceleration in this condition. Therefore, it was inferred that the nausea evoked by a Coriolis stimulus is principally caused by gyroscopic angular acceleration.
All joint moments significantly contribute to trunk angular acceleration.
Nott, Cameron R; Zajac, Felix E; Neptune, Richard R; Kautz, Steven A
2010-09-17
Computationally advanced biomechanical analyses of gait demonstrate the often counter-intuitive roles of joint moments on various aspects of gait such as propulsion, swing initiation, and balance. Each joint moment can produce linear and angular acceleration of all body segments (including those on which the moment does not directly act) due to the dynamic coupling inherent in the interconnected musculoskeletal system. This study presents quantitative relationships between individual joint moments and trunk control with respect to balance during gait to show that the ankle, knee, and hip joint moments all affect the angular acceleration of the trunk. We show that trunk angular acceleration is affected by all joints in the leg with varying degrees of dependence during the gait cycle. Furthermore, it is shown that inter-planar coupling exists and a two-dimensional analysis of trunk balance neglects important out-of-plane joint moments that affect trunk angular acceleration.
Angular dynamics of small crystals in viscous flows
Fries, Johan; Einarsson, Jonas; Mehlig, Bernhard
2016-11-01
The angular dynamics of a very small ellipsoidal particle in a viscous flow decouples from its translational dynamics, and the particle angular velocity is given by Jeffery's theory. It is known that cuboid particles share these properties. In the literature a special case is most frequently discussed, that of axisymmetric particles, with a continuous rotational symmetry. Here we compute the angular dynamics of crystals that possess a discrete rotational symmetry and certain mirror symmetries, but that do not have a continuous rotational symmetry. We give examples of such particles that nevertheless obey Jeffery's theory. But there are other examples where the angular dynamics is determined by a more general equation of motion. Vetenskapsrådet [Grant Number 2013-3992], Formas [Grant Number 2014-585], "Bottlenecks for particle growth in turbulent aerosols" from the Knut and Alice Wallenberg Foundation, Dnr. KAW 2014.0048, MPNS COST Action MP1305 "Flowing matter".
Spatial-angular modeling of ground-based biaxial lidar
Agishev, Ravil R.
1997-10-01
Results of spatial-angular LIDAR modeling based on an efficiency criterion introduced are represented. Their analysis shows that a low spatial-angular efficiency of traditional VIS and NIR systems is a main cause of a low S/BR ratio at the photodetector input. It determines the considerable measurements errors and the following low accuracy of atmospheric optical parameters retrieval. As we have shown, the most effective protection against intensive sky background radiation for ground-based biaxial LIDAR's consist in forming of their angular field according to spatial-angular efficiency criterion G. Some effective approaches to high G-parameter value achievement to achieve the receiving system optimization are discussed.
Students' Understanding of the Addition of Angular Momentum
Singh, Chandralekha
2016-01-01
We describe the difficulties advanced undergraduate and graduate students have with concepts related to the addition of angular momentum. We also describe the development and implementation of a research-based learning tool, a Quantum Interactive Learning Tutorial (QuILT), to reduce these difficulties. The preliminary evaluation shows that the QuILT on the addition of angular momentum is helpful in improving students' understanding of these concepts.
Comparison between two concepts of angular glint:general considerations
Institute of Scientific and Technical Information of China (English)
Wang Chao; Yin Hongcheng; Huang Peikang
2008-01-01
Angular glint can be interpreted as a distortion of the radar echo signal phase front,or alternatively,a tilt of the direction of energy flow from the radial direction.As the complementarities and support of argumentation in our previous work,a general discussion about two concepts of angular glint is made based on electromagnetic theory to demonstrate that these two concepts are equivalent when geometrical optics approximation is used and the receiving antenna is linearly polarized.
Four Cases of Angular Cheilitis in Orthodontic Patients
P Kafaie; S Yassaei
2006-01-01
Contact dermatitis is an inflammatory reaction of the skin and mucosa to either external or internal factors. It can be divided to two forms of irritant contact dermatitis and allergic contact dermatitis. Nickel is one of the most common materials that causes allergic contact dermatitis and is widely used in orthodontic appliances. The inflammatory reaction to this metal in orthodontics is usually stomatitis and angular cheilitis is very rare. We report 4 cases of angular cheilitis in orthodo...
On the angular distribution of extensive air showers
Zotov, M Yu; Kulikov, G V; Sulakov, V P
2009-01-01
Angular distributions of extensive air showers with different number of charged particles in the range 2.5x10^5--4x10^7 are derived using the experimental data obtained with the EAS MSU array. Possible approximations of the obtained distributions with different empiric functions available in literature, are analysed. It is shown that the exponential function provides the best approximation of the angular distributions in the sense of the chi-squared criterion.
Relativistic electron ring equilibrium with angular momentum spread
Energy Technology Data Exchange (ETDEWEB)
Croitoru, M.; Grecu, D. (Institutul de Fizica si Inginerie Nucleara, Bucharest (Romania))
1980-01-01
The equilibrium properties of a relativistic electron ring are determined by solving in a consistent way the Vlasov-Maxwell equations for a distribution function with an angular momentum spread. In the thin ring approximation there have been deduced general formulae for the electron density and the current density. A general theorem concerning the sharp form in space of the electron density is also obtained for the case of a microcanonical distribution function both in energy and angular momentum.
Diffraction by a plane angular sector, a new derivation
DEFF Research Database (Denmark)
Hansen, Thokild B.
1990-01-01
An alternative derivation is given for the exact solution to the scattering problem in which a Hertz dipole illuminates a perfectly conducting plane angular sector. Specifically, the Ohm-Rayleigh method is used rather than that of Satterwhite (1969)......An alternative derivation is given for the exact solution to the scattering problem in which a Hertz dipole illuminates a perfectly conducting plane angular sector. Specifically, the Ohm-Rayleigh method is used rather than that of Satterwhite (1969)...
NUTRITIONAL STATUS ASSOCIATION WITH ANGULAR CHEILITIS IN PRIMARY STUDENT AGE
Sumintarti, Sumintarti
2013-01-01
ABSTRACT Student in primary level school is in fast and active growth. In this growth stage, they have to supplied by high enough nutrition in exact quality and quantity otherwise they will suffer with some oral disease such as angular cheilitis. This study aimed to measured any association of nutritional status and angular cheilitis occurrence in primary student of Lae-Lae II and Pampang elementary state schools. We used observational analytic with purposive sampling method. All student...
A Role for Improved Angular Observations in Geosynchronous Orbit Determination
Sabol, Christopher Andrew
1998-12-01
The goal of this thesis is to show that improved angular observations can aid in the determination of satellite position and velocity in the geosynchronous orbit regime. Raven is a new sensor being developed by the U.S. Air Force Research Laboratory which should allow for angular observations of satellites to be made with a standard deviation of 1 arcsecond (which maps into approximately 170 meters at geosynchronous altitude); this is an order of magnitude improvement over traditional angular observation techniques and represents state of the art accuracy of angular observations for geosynchronous orbit determination work. Simulation studies are undertaken to show that these angular observations can be used in the orbit determination process both as the only cracking data source and as a supplement to other tracking data sources such as radar and radio transponder ranges. Results from the radio transponder range analysis are extended to cover Satellite Laser Ranging (SLR) and Global Positioning System (GPS) observation types as well. The studies target both space surveillance and owner/operator mission support aspects of orbit determination although the emphasis will be on mission support satellite operations. Parameters varied in the simulation studies include the number of observing stations, the density of the angular observations, and the number of nights of optical tracking. The data simulations are calibrated based on real data results from a geosynchronous satellite to ensure the integrity of the simulations and the accuracy of the results. The studies show that including the improved angular observations with traditional high accuracy range observations produces a significant improvement in orbit determination accuracy over the range observations alone. The studies also show single site geosynchronous orbit determination is an attractive alternative when combining improved angular and high accuracy range observations.
Statistical Angular Resolution Limit for Ultrawideband MIMO Noise Radar
2015-01-01
The two-dimensional angular resolution limit (ARL) of elevation and azimuth for MIMO radar with ultrawideband (UWB) noise waveforms is investigated using statistical resolution theory. First, the signal model of monostatic UWB MIMO noise radar is established in a 3D reference frame. Then, the statistical angular resolution limits (SARLs) of two closely spaced targets are derived using the detection-theoretic and estimation-theoretic approaches, respectively. The detection-theoretic approach i...
Exceptional Parent, 1987
1987-01-01
Suggestions are presented for helping disabled individuals learn to use or adapt toothbrushes for proper dental care. A directory lists dental health instructional materials available from various organizations. (CB)
DEFF Research Database (Denmark)
Møller Larsen, Marcus; Lyngsie, Jacob
We investigate why some exchange relationships terminate prematurely. We argue that investments in informal governance structures induce premature termination in relationships already governed by formal contracts. The formalized adaptive behavior of formal governance structures and the flexible a...
2008-01-01
People live in a world in which they are surrounded by potential disgust elicitors such as ``used'' chairs, air, silverware, and money as well as excretory activities. People function in this world by ignoring most of these, by active avoidance, reframing, or adaptation. The issue is particularly striking for professions, such as morticians, surgeons, or sanitation workers, in which there is frequent contact with major disgust elicitors. In this study, we study the ``adaptation'' process to d...
DEFF Research Database (Denmark)
Andersen, Torben Juul
2015-01-01
This article provides an overview of theoretical contributions that have influenced the discourse around strategic adaptation including contingency perspectives, strategic fit reasoning, decision structure, information processing, corporate entrepreneurship, and strategy process. The related...... concepts of strategic renewal, dynamic managerial capabilities, dynamic capabilities, and strategic response capabilities are discussed and contextualized against strategic responsiveness. The insights derived from this article are used to outline the contours of a dynamic process of strategic adaptation...
Is adaptation. Truly an adaptation? Is adaptation. Truly an adaptation?
Directory of Open Access Journals (Sweden)
Thais Flores Nogueira Diniz
2008-04-01
Full Text Available The article begins by historicizing film adaptation from the arrival of cinema, pointing out the many theoretical approaches under which the process has been seen: from the concept of “the same story told in a different medium” to a comprehensible definition such as “the process through which works can be transformed, forming an intersection of textual surfaces, quotations, conflations and inversions of other texts”. To illustrate this new concept, the article discusses Spike Jonze’s film Adaptation. according to James Naremore’s proposal which considers the study of adaptation as part of a general theory of repetition, joined with the study of recycling, remaking, and every form of retelling. The film deals with the attempt by the scriptwriter Charles Kaufman, cast by Nicholas Cage, to adapt/translate a non-fictional book to the cinema, but ends up with a kind of film which is by no means what it intended to be: a film of action in the model of Hollywood productions. During the process of creation, Charles and his twin brother, Donald, undergo a series of adventures involving some real persons from the world of film, the author and the protagonist of the book, all of them turning into fictional characters in the film. In the film, adaptation then signifies something different from itstraditional meaning. The article begins by historicizing film adaptation from the arrival of cinema, pointing out the many theoretical approaches under which the process has been seen: from the concept of “the same story told in a different medium” to a comprehensible definition such as “the process through which works can be transformed, forming an intersection of textual surfaces, quotations, conflations and inversions of other texts”. To illustrate this new concept, the article discusses Spike Jonze’s film Adaptation. according to James Naremore’s proposal which considers the study of adaptation as part of a general theory of repetition
System Dynamics and Adaptive Control for MEMS Gyroscope Sensor
Directory of Open Access Journals (Sweden)
Juntao Fei
2011-01-01
Full Text Available This paper presents an adaptive control approach for Micro-Electro-Mechanical Systems (MEMS z-axis gyroscope sensor. The dynamical model of MEMS gyroscope sensor is derived and adaptive state tracking control for MEMS gyroscope is developed. The proposed adaptive control approaches can estimate the angular velocity and the damping and stiffness coefficients including the coupling terms due to the fabrication imperfection. The stability of the closed-loop systems is established with the proposed adaptive control strategy. Numerical simulation is investigated to verify the effectiveness of the proposed control scheme.
Smoothed dissipative particle dynamics with angular momentum conservation
Energy Technology Data Exchange (ETDEWEB)
Müller, Kathrin, E-mail: k.mueller@fz-juelich.de; Fedosov, Dmitry A., E-mail: d.fedosov@fz-juelich.de; Gompper, Gerhard, E-mail: g.gompper@fz-juelich.de
2015-01-15
Smoothed dissipative particle dynamics (SDPD) combines two popular mesoscopic techniques, the smoothed particle hydrodynamics and dissipative particle dynamics (DPD) methods, and can be considered as an improved dissipative particle dynamics approach. Despite several advantages of the SDPD method over the conventional DPD model, the original formulation of SDPD by Español and Revenga (2003) [9], lacks angular momentum conservation, leading to unphysical results for problems where the conservation of angular momentum is essential. To overcome this limitation, we extend the SDPD method by introducing a particle spin variable such that local and global angular momentum conservation is restored. The new SDPD formulation (SDPD+a) is directly derived from the Navier–Stokes equation for fluids with spin, while thermal fluctuations are incorporated similarly to the DPD method. We test the new SDPD method and demonstrate that it properly reproduces fluid transport coefficients. Also, SDPD with angular momentum conservation is validated using two problems: (i) the Taylor–Couette flow with two immiscible fluids and (ii) a tank-treading vesicle in shear flow with a viscosity contrast between inner and outer fluids. For both problems, the new SDPD method leads to simulation predictions in agreement with the corresponding analytical theories, while the original SDPD method fails to capture properly physical characteristics of the systems due to violation of angular momentum conservation. In conclusion, the extended SDPD method with angular momentum conservation provides a new approach to tackle fluid problems such as multiphase flows and vesicle/cell suspensions, where the conservation of angular momentum is essential.
Adaptive transmit selection with interference suppression
Radaydeh, Redha Mahmoud Mesleh
2010-01-01
This paper studies the performance of adaptive transmit channel selection in multipath fading channels. The adaptive selection algorithms are configured for single-antenna bandwidth-efficient or power-efficient transmission with as low transmit channel estimations as possible. Due to the fact that the number of active co-channel interfering signals and their corresponding powers experience random behavior, the adaptation to channels conditions, assuming uniform buffer and traffic loading, is proposed to be jointly based on the transmit channels instantaneous signal-to-noise ratios (SNRs) and signal-to- interference-plus- noise ratios (SINRs). Two interference cancelation algorithms, which are the dominant cancelation and the less complex arbitrary cancelation, are considered, for which the receive antenna array is assumed to have small angular spread. Analytical formulation for some performance measures in addition to several processing complexity and numerical comparisons between various adaptation schemes are presented. ©2010 IEEE.
A micromachined angular-acceleration sensor for geophysical applications
Liu, Huafeng; Pike, W. T.
2016-10-01
This paper presents an angular-acceleration sensor that works as either an angular accelerometer or a gravity gradiometer and is based on the micro electromechanical system (MEMS) technology. The changes in the angle of the sensor mass are sensed by a rotational capacitive array transducer that is formed by electrodes on both the stator and rotor dies of the flip-chip-bonded MEMS chip (21 mm × 12.5 mm × 1 mm). The prototype was characterized, demonstrating a fundamental frequency of 27 Hz, a quality factor of 230 in air, and a sensitivity of 6 mV/(rad/s2). The demonstrated noise floor was less than 0.003 rad/s2/ √{ Hz } within a bandwidth of 0.1 Hz to 10 Hz, which is comparable with the conventional angular accelerometer and is better than the other reported MEMS sensors in low-frequency ranges. The features of small size and low cost suggest that this MEMS angular-acceleration sensor could be mounted on a drone, a satellite or even a Mars rover, and it is promising to be used for monitoring angular accelerations, aiding seismic recording, mapping gravity anomalies, and other geophysical applications for large-scale terrestrial and space deployments.
The human ocular torsion position response during yaw angular acceleration.
Smith, S T; Curthoys, I S; Moore, S T
1995-07-01
Recent results by Wearne [(1993) Ph.D. thesis] using the scleral search-coil method of measuring eye position indicate that changes in ocular torsion position (OTP) occur during yaw angular acceleration about an earth vertical axis. The present set of experiments, using an image processing method of eye movement measurement free from the possible confound of search coil slippage, demonstrates the generality and repeatability of this phenomenon and examines its possible causes. The change in torsion position is not a linear vestibulo-ocular reflex (LVOR) response to interaural linear acceleration stimulation of the otoliths, but rather the effect is dependent on the characteristics of the angular acceleration stimulus, commencing at the onset and decaying at the offset of the angular acceleration. In the experiments reported here, the magnitude of the angular acceleration stimulus was varied and the torsion position response showed corresponding variations. We consider that the change in torsion position observed during angular acceleration is most likely to be due to activity of the semicircular canals.
Polarization control of single photon quantum orbital angular momentum states.
Nagali, E; Sciarrino, F; De Martini, F; Piccirillo, B; Karimi, E; Marrucci, L; Santamato, E
2009-10-12
The orbital angular momentum of photons, being defined in an infinite-dimensional discrete Hilbert space, offers a promising resource for high-dimensional quantum information protocols in quantum optics. The biggest obstacle to its wider use is presently represented by the limited set of tools available for its control and manipulation. Here, we introduce and test experimentally a series of simple optical schemes for the coherent transfer of quantum information from the polarization to the orbital angular momentum of single photons and vice versa. All our schemes exploit a newly developed optical device, the so-called "q-plate", which enables the manipulation of the photon orbital angular momentum driven by the polarization degree of freedom. By stacking several q-plates in a suitable sequence, one can also have access to higher-order angular momentum subspaces. In particular, we demonstrate the control of the orbital angular momentum m degree of freedom within the subspaces of |m| = 2h and |m| = 4h per photon.
Functional phases and angular momentum characteristics of Tkatchev and Kovacs.
Irwin, Gareth; Exell, Timothy A; Manning, Michelle L; Kerwin, David G
2017-03-01
Understanding the technical requirements and underlying biomechanics of complex release and re-grasp skills on high bar allows coaches and scientists to develop safe and effective training programmes. The aim of this study was to examine the differences in the functional phases between the Tkatchev and Kovacs skills and to explain how the angular momentum demands are addressed. Images of 18 gymnasts performing 10 Tkatchevs and 8 Kovacs at the Olympic Games were recorded (50 Hz), digitised and reconstructed (3D Direct Linear Transformation). Orientation of the functional phase action, defined by the rapid flexion to extension of the shoulders and extension to flexion of the hips as the performer passed through the lower vertical, along with shoulder and hip angular kinematics, angular momentum and key release parameters (body angle, mass centre velocity and angular momentum about the mass centre and bar) were compared between skills. Expected differences in the release parameters of angle, angular momentum and velocity were observed and the specific mechanical requirement of each skill were highlighted. Whilst there were no differences in joint kinematics, hip and shoulder functional phase were significantly earlier in the circle for the Tkatchev. These findings highlight the importance of the orientation of the functional phase in the preceding giant swing and provide coaches with further understanding of the critical timing in this key phase.
Gamma-Gamma Angular Correlation Measurements With GRIFFIN
Maclean, Andrew; Griffin Collaboration
2016-09-01
The goal of this work was to explore the sensitivity of the Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei (GRIFFIN) 16 clover-detector γ-ray spectrometer at TRIUMF-ISAC to such γ - γ angular correlations. The methodology was established using both experimental measurements and Geant4 simulations that were used to create angular correlation templates for the GRIFFIN geometry. Direct comparisons were made between experimental data sets and the simulated angular correlation templates. A first in-beam test of the γ - γ angular correlation measurements with GRIFFIN was performed with a radioactive beam of 66Ga. Mixing ratios of δ = - 2 . 1(2) and δ = - 0 . 08(3) were measured for the 2+ ->2+ ->0+ 833-1039 keV and 1+ ->2+ ->0+ 2752-1039 keV cascades in the daughter nucleus 66Zn. These results are in good agreement with pervious literature values and the mixing ratio for the 833-1039 keV cascade has a higher precision. Also, the sensitivity to the 1333-1039 keV cascade, with its pronounced 0+ ->2+ ->0+ angular correlation, was measured.A test measurement of the superallowed Fermi β emitter 62Ga will also be discussed. Canada Foundation of Innovation, Natural Sciences and Engineering Research Council of Canada, National Research Council of Canada and Canadian Research Chairs Program.
The human vestibulo-ocular reflex : effects of adaptation
L.J.J.M. Boumans (Leon)
1982-01-01
textabstractThis thesis systematically investigates the influence of adaptation on the human VOR-response. Various types of angular acceleration around the vertical axis are used to determine the time constants of the VOR-system. Care is taken as far as possible to avoid fatigue, habituation and the
DEFF Research Database (Denmark)
Kjeldsen, Lars Peter; Rose, Mette
2010-01-01
Artikelen er en evaluering af de adaptive tests, som blev indført i folkeskolen. Artiklen sætter særligt fokus på evaluering i folkeskolen, herunder bidrager den med vejledning til evaluering, evalueringsværktøjer og fagspecifkt evalueringsmateriale.......Artikelen er en evaluering af de adaptive tests, som blev indført i folkeskolen. Artiklen sætter særligt fokus på evaluering i folkeskolen, herunder bidrager den med vejledning til evaluering, evalueringsværktøjer og fagspecifkt evalueringsmateriale....
Is the angular momentum of an electron conserved in a uniform magnetic field?
Greenshields, Colin R; Stamps, Robert L; Franke-Arnold, Sonja; Barnett, Stephen M
2014-12-12
We show that an electron moving in a uniform magnetic field possesses a time-varying "diamagnetic" angular momentum. Surprisingly this means that the kinetic angular momentum of the electron may vary with time, despite the rotational symmetry of the system. This apparent violation of angular momentum conservation is resolved by including the angular momentum of the surrounding fields.
The large-scale angular correlations in CMB temperature maps
Bernui, A
2005-01-01
Observations show that the Cosmic Microwave Background (CMB) contains tiny variations at the 10^{-5} level around its black-body equilibrium temperature. The detection of these temperature fluctuations provides to modern Cosmology evidence for the existence of primordial density perturbations that seeded all the structures presently observed. The vast majority of the cosmological information is contained in the 2-point temperature function, which measures the angular correlation of these temperature fluctuations distributed on the celestial sphere. Here we study such angular correlations using a recently introduced statistic-geometrical method. Moreover, we use Monte Carlo simulated CMB temperature maps to show the equivalence of this method with the 2-point temperature function (best known as the 2-Point Angular Correlation Function). We also investigate here the robustness of this new method under possible divisions of the original catalog-data in sub-catalogs. Finally, we show some applications of this new...
A Differential Reflective Intensity Optical Fiber Angular Displacement Sensor.
Jia, Binghui; He, Lei; Yan, Guodong; Feng, Yong
2016-09-16
In this paper, a novel differential reflective intensity optical fiber angular displacement sensor was proposed. This sensor can directly measure the angular and axial linear displacement of a flat surface. The structure of the sensor probe is simple and its basic principle was first analyzed according to the intensity modulation mechanisms. Secondly, in order to trim the dark output voltage to zero, the photoelectric conversion circuit was developed to adjust the signals. Then, the sensor model including the photoelectric conversion circuit has been established, and the influence of design parameters on the sensor output characteristic has been simulated. Finally, the design parameters of the sensor structure were obtained based on the simulation results; and an experimental test system was built for the sensor calibration. Experimental results show that the linear angular range and the sensitivity of the sensor were 74.4 and 0.051 V/°, respectively. Its change rules confirm the operating principle of the sensor well.
Transfer of optical orbital angular momentum to a bound electron
Schmiegelow, Christian T.; Schulz, Jonas; Kaufmann, Henning; Ruster, Thomas; Poschinger, Ulrich G.; Schmidt-Kaler, Ferdinand
2016-10-01
Photons can carry angular momentum, not only due to their spin, but also due to their spatial structure. This extra twist has been used, for example, to drive circular motion of microscopic particles in optical tweezers as well as to create vortices in quantum gases. Here we excite an atomic transition with a vortex laser beam and demonstrate the transfer of optical orbital angular momentum to the valence electron of a single trapped ion. We observe strongly modified selection rules showing that an atom can absorb two quanta of angular momentum from a single photon: one from the spin and another from the spatial structure of the beam. Furthermore, we show that parasitic ac-Stark shifts from off-resonant transitions are suppressed in the dark centre of vortex beams. These results show how light's spatial structure can determine the characteristics of light-matter interaction and pave the way for its application and observation in other systems.
Nanoradian angular stabilization of x-ray optical components.
Stoupin, Stanislav; Lenkszus, Frank; Laird, Robert; Goetze, Kurt; Kim, Kwang-Je; Shvyd'ko, Yuri
2010-05-01
An x-ray free-electron laser oscillator (XFELO) has been recently proposed [K. Kim et al., Phys. Rev. Lett. 100, 244802 (2008)]. Angular orientation and position in space of Bragg mirrors of the XFELO optical cavity must be continuously adjusted to compensate for the instabilities and maximize the output intensity. An angular stability of about 10 nrad (rms) is required [K. Kim and Y. Shvyd'ko, Phys. Rev. ST Accel. Beams 12, 030703 (2009)]. To approach this goal, a feedback loop based on a null-detection principle was designed and used for stabilization of a high-energy-resolution x-ray monochromator (DeltaE/E approximately 4 x 10(-8), E=23.7 keV) and a high-heat-load monochromator. Angular stability of about 13 nrad (rms) has been demonstrated for x-ray optical elements of the monochromators.
Nanoradian angular stabilization of x-ray optical components
Stoupin, Stanislav; Laird, Robert; Goetze, Kurt; Kim, Kwang-Je; Shvydko, Yuri
2010-01-01
An x-ray free electron laser oscillator (XFELO) has been recently proposed [K. Kim, Y. Shvyd'ko, and S. Reiche, Phys. Rev. Lett. 100, 244802 (2008)]. Angular orientation and position in space of Bragg mirrors of the XFELO optical cavity must be continuously adjusted to compensate instabilities and maximize the output intensity. An angular stability of about 10 nrad (rms) is required [K. Kim and Y. Shvyd'ko Phys. Rev. STAB 12, 030703 (2009)]. To approach this goal, a feedback loop based on a null-detection principle was designed and used for stabilization of a high energy resolution x-ray monochromator ($\\Delta E/E \\simeq 4 \\times 10^{-8}$, $E$ = 23.7 keV) and a high heat load monochromator. Angular stability of about 13 nrad (rms) has been demonstrated for x-ray optical elements of the monochromators.
A Differential Reflective Intensity Optical Fiber Angular Displacement Sensor
Jia, Binghui; He, Lei; Yan, Guodong; Feng, Yong
2016-01-01
In this paper, a novel differential reflective intensity optical fiber angular displacement sensor was proposed. This sensor can directly measure the angular and axial linear displacement of a flat surface. The structure of the sensor probe is simple and its basic principle was first analyzed according to the intensity modulation mechanisms. Secondly, in order to trim the dark output voltage to zero, the photoelectric conversion circuit was developed to adjust the signals. Then, the sensor model including the photoelectric conversion circuit has been established, and the influence of design parameters on the sensor output characteristic has been simulated. Finally, the design parameters of the sensor structure were obtained based on the simulation results; and an experimental test system was built for the sensor calibration. Experimental results show that the linear angular range and the sensitivity of the sensor were 74.4 and 0.051 V/°, respectively. Its change rules confirm the operating principle of the sensor well. PMID:27649199
The angular magnetothermoelectric power of a charge density wave system
Krstovska, D.; Choi, E. S.; Steven, E.; Brooks, J. S.
2012-07-01
The angular dependence of the magnetothermopower of a charge transfer organic salt α-(ET)2KHg(SCN)4 below (4 K) and above (9 K) the phase transition temperature, Tp = 8 K, and under fields of 15 T and 25 T, below and above the ‘kinkfield’, has been studied. We find that for a longitudinal thermoelectric measurement both an interlayer thermopower (the Seebeck effect), Szz, and a transverse thermopower (the Nernst effect), Syz, exist in all three different B-T phases (the CDW 0, CDW x and metallic states) with large amplitude. Both thermoelectric effects display a resonant-like behavior without a sign reversal at the angles corresponding to angular magnetoresistance oscillation minima and maxima in this compound. The resonant behavior is most evident in the CDW0 state, indicating a mechanism involving the Fermi surface nesting. Angular dependences reveal different behaviors of the thermopower and Nernst effect in the high magnetic field (CDWx) state.
Angular anisotropy of the fusion-fission and quasifission fragments
Nasirov, A K; Utamuratov, R K; Fazio, G; Giardina, G; Hanappe, F; Mandaglio, G; Manganaro, M; Scheid, W
2007-01-01
The anisotropy in the angular distribution of the fusion-fission and quasifission fragments for the $^{16}$O+$^{238}$U, $^{19}$F+$^{208}$Pb and $^{32}$S+$^{208}$Pb reactions is studied by analyzing the angular momentum distributions of the dinuclear system and compound nucleus which are formed after capture and complete fusion, respectively. The orientation angles of axial symmetry axes of colliding nuclei to the beam direction are taken into account for the calculation of the variance of the projection of the total spin onto the fission axis. It is shown that the deviation of the experimental angular anisotropy from the statistical model picture is connected with the contribution of the quasifission fragments which is dominant in the $^{32}$S+$^{208}$Pb reaction. Enhancement of anisotropy at low energies in the $^{16}$O+$^{238}$U reaction is connected with quasifission of the dinuclear system having low temperature and effective moment of inertia.
Conservation of orbital angular momentum in air core optical fibers
Gregg, P; Ramachandran, S
2014-01-01
Light's orbital angular momentum (OAM) is a conserved quantity in cylindrically symmetric media; however, it is easily destroyed by free-space turbulence or fiber bends, because anisotropic perturbations impart angular momentum. We observe the conservations of OAM even in the presence of strong bend perturbations, with fibers featuring air cores that appropriately sculpt the modal density of states. In analogy to the classical reasoning for the enhanced stability of spinning tops with increasing angular velocity, these states' lifetimes with OAM magnitude. Consequently, contrary to convention wisdom that ground states of systems are the most stable, OAM longevity in air-core fiber increases with mode order. Aided by conservation of this fundamental quantity, we demonstrate fiber propagation of 12 distinct higher-order OAM modes, of which 8 remain low-loss and >98% pure from near-degenerate coupling after km-length propagation. The first realization of long-lived higher-order OAM states, thus far posited to ex...
Angular distributions for two-photon double ionization of lithium
Armstrong, G. S. J.; Colgan, J.
2012-08-01
We present angular distributions for two-photon double ionization of lithium at photon energies of 50 eV (λ = 25 nm) and 59 eV (λ = 21 nm). The results are obtained from full-dimensional solution of the two-active-electron time-dependent Schrödinger equation using the time-dependent close-coupling method. We investigate two different double ionization mechanisms. First, we consider direct double ionization of the Li ground state following the absorption of two photons. Secondly, we consider an initial photoexcitation of the 1s2s2p doubly excited state, followed by photoionization of the 2s and 2p electrons. We find significant differences between the angular distributions obtained for these two distinct processes. We also compare the characteristics of the angular distributions for Li with those of other two-electron atoms.
Valley-contrasting orbital angular momentum in photonic valley crystals
Chen, Xiaodong; Dong, Jianwen
2016-01-01
Valley, as a degree of freedom, has been exploited to realize valley-selective Hall transport and circular dichroism in two-dimensional layered materials. On the other hand, orbital angular momentum of light with helical phase distribution has attracted great attention for its unprecedented opportunity to optical communicagtions, atom trapping, and even nontrivial topology engineering. Here, we reveal valley-contrasting orbital angular momentum in all-dielectric photonic valley crystals. Selective excitation of valley chiral bulk states is realized by sources carrying orbital angular momentum with proper chirality. Valley dependent edge states, predictable by nonzero valley Chern number, enable to suppress the inter-valley scattering along zigzag boundary, leading to broadband robust transmission in Z-shape bend without corner morphological optimization. Our work may open up a new door towards the discovery of novel quantum states and the manipulation of spin-orbit interaction of light in nanophotonics.
Probing angular momentum coherence in a twin-atom interferometer
de Carvalho, Carlos R; Impens, François; Robert, J; Medina, Aline; Zappa, F; Faria, N V de Castro
2014-01-01
We propose to use a double longitudinal Stern-Gerlach atom interferometer in order to investigate quantitatively the angular momentum coherence of molecular fragments. Assuming that the dissociated molecule has a null total angular momentum, we investigate the propagation of the corresponding atomic fragments in the apparatus. We show that the envisioned interferometer enables one to distinguish unambiguously a spin-coherent from a spin-incoherent dissociation, as well as to estimate the purity of the angular momentum density matrix associated with the fragments. This setup, which may be seen as an atomic analogue of a twin-photon interferometer, can be used to investigate the suitability of molecule dissociation processes -- such as the metastable hydrogen atoms H($2^2 S$)-H($2^2 S$) dissociation - for coherent twin-atom optics.
Fractional angular momentum in cold-atom systems.
Zhang, Yuhe; Sreejith, G J; Gemelke, N D; Jain, J K
2014-10-17
The quantum statistics of bosons or fermions are manifest through the even or odd relative angular momentum of a pair. We show theoretically that, under certain conditions, a pair of certain test particles immersed in a fractional quantum Hall state possesses, effectively, a fractional relative angular momentum, which can be interpreted in terms of fractional braid statistics. We propose that the fractionalization of the angular momentum can be detected directly through the measurement of the pair correlation function in rotating ultracold atomic systems in the fractional quantum Hall regime. Such a measurement will also provide direct evidence for the effective magnetic field resulting from Berry phases arising from attached vortices, and of excitations with a fractional particle number, analogous to the fractional charge of the electron fractional quantum Hall effect.
On-chip noninterference angular momentum multiplexing of broadband light.
Ren, Haoran; Li, Xiangping; Zhang, Qiming; Gu, Min
2016-05-13
Angular momentum division has emerged as a physically orthogonal multiplexing method in high-capacity optical information technologies. However, the typical bulky elements used for information retrieval from the overall diffracted field, based on the interference method, impose a fundamental limit toward realizing on-chip multiplexing. We demonstrate noninterference angular momentum multiplexing by using a mode-sorting nanoring aperture with a chip-scale footprint as small as 4.2 micrometers by 4.2 micrometers, where nanoring slits exhibit a distinctive outcoupling efficiency on tightly confined plasmonic modes. The nonresonant mode-sorting sensitivity and scalability of our approach enable on-chip parallel multiplexing over a bandwidth of 150 nanometers in the visible wavelength range. The results offer the possibility of ultrahigh-capacity and miniaturized nanophotonic devices harnessing angular momentum division.
Transfer of orbital angular momentum through sub-wavelength waveguides.
Wang, Yanqin; Ma, Xiaoliang; Pu, Mingbo; Li, Xiong; Huang, Cheng; Pan, Wenbo; Zhao, Bo; Cui, Jianhua; Luo, Xiangang
2015-02-01
Data capacity of optical communication is achieving its limit owing to the non-linear effect of optical fiber. As an effective alternative, light carrying orbital angular momentum can greatly increase the capacity for its unprecedented degree of freedom. We demonstrate the propagation of orbital angular momentum with topological charge of 1 and 2 in plasmonic circular waveguide with sub-wavelength diameter with little propagation loss of 2.73 dB/μm, which has never been observed in optical fibers with sub-wavelength diameter. We also confirm that lights carrying orbital angular momentum can be maintained in sharp bended sub-wavelength waveguide. This plasmonic waveguide may serve as a key component in on-chip systems involving OAM.
Fractional Angular Momentum in Cold-Atom Systems
Zhang, Yuhe; Sreejith, G. J.; Gemelke, N. D.; Jain, J. K.
2014-10-01
The quantum statistics of bosons or fermions are manifest through the even or odd relative angular momentum of a pair. We show theoretically that, under certain conditions, a pair of certain test particles immersed in a fractional quantum Hall state possesses, effectively, a fractional relative angular momentum, which can be interpreted in terms of fractional braid statistics. We propose that the fractionalization of the angular momentum can be detected directly through the measurement of the pair correlation function in rotating ultracold atomic systems in the fractional quantum Hall regime. Such a measurement will also provide direct evidence for the effective magnetic field resulting from Berry phases arising from attached vortices, and of excitations with a fractional particle number, analogous to the fractional charge of the electron fractional quantum Hall effect.
Orbital angular momentum of scalar field generated by gravitational scatterings
Nishikawa, Ryusuke; Masuda, Atsuki; Nambu, Yasusada; Ishihara, Hideki
2016-01-01
It has been expected that astronomical observations to detect the orbital angular momenta of electromagnetic waves may give us a new insight into astrophysics. Previous works pointed out the possibility that a rotating black hole can produce orbital angular momenta of electromagnetic waves through gravitational scattering, and the spin parameter of the black hole can be measured by observing them. However, the mechanism how the orbital angular momentum of the electromagnetic wave is generated by the gravitational scattering has not been clarified sufficiently. In this paper, in order to understand it from a point of view of gravitational lensing effects, we consider an emitter which radiates a spherical wave of the real massless scalar field and study the deformation of the scalar wave by the gravitational scattering due to a black hole by invoking the geometrical optics approximation. We show that the frame dragging caused by the rotating black hole is not a necessary condition for generating the orbital ang...
Rivola, Alessandro; Troncossi, Marco
2014-02-01
An experimental test campaign was performed on the valve train of a racing motorbike engine in order to get insight into the dynamic of the system. In particular the valve motion was acquired in cold test conditions by means of a laser vibrometer able to acquire displacement and velocity signals. The valve time-dependent measurements needed to be referred to the camshaft angular position in order to analyse the data in the angular domain, as usually done for rotating machines. To this purpose the camshaft was fitted with a zebra tape whose dark and light stripes were tracked by means of an optical probe. Unfortunately, both manufacturing and mounting imperfections of the employed zebra tape, resulting in stripes with slightly different widths, precluded the possibility to directly obtain the correct relationship between camshaft angular position and time. In order to overcome this problem, the identification of the zebra tape was performed by means of the original and practical procedure that is the focus of the present paper. The method consists of three main steps: namely, an ad-hoc test corresponding to special operating conditions, the computation of the instantaneous angular speed, and the final association of the stripes with the corresponding shaft angular position. The results reported in the paper demonstrate the suitability of the simple procedure for the zebra tape identification performed with the final purpose to implement a computed order tracking technique for the data analysis.
Johnson-Groh, Mara; Ellison, Sara L
2016-01-01
The advantages of angular differential imaging (ADI) has been previously untested in imaging the host galaxies of damped Lyman alpha (DLA) systems. In this pilot study, we present the first application of ADI to directly imaging the host galaxy of the DLA seen towards the quasar J1431+3952. K-band imaging of the field surrounding J1431+3952 was obtained on the Gemini North telescope with the adaptive optics system and a laser guide star. We computed a sensitivity curve that demonstrates the sensitivity of our observations as a function of K-band magnitude, impact parameter and DLA angular size. For an impact parameter of 0.5" (3.4 kpc at the redshift of the absorber) our mass sensitivity is log (M_star/M_sun) ~ 9.2 and drops to ~ 9.0 at separations beyond ~ 6 kpc for the smallest size model galaxy. Three candidate galaxies are identified within 5". Stellar masses were computed from the K-band photometry yielding values of log (M_star/M_sun) ~ 9.9, 9.7 and 11.1 respectively. The likely identification of the ab...
Optimizations in angular dispersive neutron powder diffraction using divergent beam geometries
Buchsteiner, Alexandra; Stüßer, Norbert
2009-01-01
Angular dispersive neutron powder diffractometers are usually built using beam divergencies defined by Soller type collimators. To account for the needs of resolution for crystal structure refinement a good in-pile collimation α1, a high take-off angle above 90∘ at the monochromator and a good collimation α3 in front of the detector bank are chosen whereas the value of α2 for the collimation between monochromator and sample is less crucial. During the last years new strategies were developed at our institute using wide divergent beam geometries defined by fan collimators or slit-type diaphragms which correlate ray direction and wavelength within the beam. Here we present the performance of a newly developed fan collimator, which enables one to adjust the opening of the collimator channels on both sides independently. This fan collimator is positioned in front of the monochromator at the instrument E6 at the Helmholtz Centre Berlin (formerly Hahn-Meitner-Institut Berlin). It will be shown that control of the beam divergency allows optimization of the resolution in a large angular diffraction range. Hence the resolution and intensity can be adapted to the needs of powder diffraction. Monte Carlo simulations using McStas are used to check and prove the optimal setting of the instrument. We obtain a very good agreement between experimental and simulated data and demonstrate the superior outcome of the new instrument configuration with respect to Soller type instruments.
Optimizations in angular dispersive neutron powder diffraction using divergent beam geometries
Energy Technology Data Exchange (ETDEWEB)
Buchsteiner, Alexandra [Helmholtz Centre Berlin for Materials and Energy, Glienicker Str. 100, D-14109 Berlin (Germany)], E-mail: buchsteiner@helmholtz-berlin.de; Stuesser, Norbert [Helmholtz Centre Berlin for Materials and Energy, Glienicker Str. 100, D-14109 Berlin (Germany)
2009-01-11
Angular dispersive neutron powder diffractometers are usually built using beam divergencies defined by Soller type collimators. To account for the needs of resolution for crystal structure refinement a good in-pile collimation {alpha}{sub 1}, a high take-off angle above 90 deg. at the monochromator and a good collimation {alpha}{sub 3} in front of the detector bank are chosen whereas the value of {alpha}{sub 2} for the collimation between monochromator and sample is less crucial. During the last years new strategies were developed at our institute using wide divergent beam geometries defined by fan collimators or slit-type diaphragms which correlate ray direction and wavelength within the beam. Here we present the performance of a newly developed fan collimator, which enables one to adjust the opening of the collimator channels on both sides independently. This fan collimator is positioned in front of the monochromator at the instrument E6 at the Helmholtz Centre Berlin (formerly Hahn-Meitner-Institut Berlin). It will be shown that control of the beam divergency allows optimization of the resolution in a large angular diffraction range. Hence the resolution and intensity can be adapted to the needs of powder diffraction. Monte Carlo simulations using McStas are used to check and prove the optimal setting of the instrument. We obtain a very good agreement between experimental and simulated data and demonstrate the superior outcome of the new instrument configuration with respect to Soller type instruments.
Adaptive compressive sensing camera
Hsu, Charles; Hsu, Ming K.; Cha, Jae; Iwamura, Tomo; Landa, Joseph; Nguyen, Charles; Szu, Harold
2013-05-01
We have embedded Adaptive Compressive Sensing (ACS) algorithm on Charge-Coupled-Device (CCD) camera based on the simplest concept that each pixel is a charge bucket, and the charges comes from Einstein photoelectric conversion effect. Applying the manufactory design principle, we only allow altering each working component at a minimum one step. We then simulated what would be such a camera can do for real world persistent surveillance taking into account of diurnal, all weather, and seasonal variations. The data storage has saved immensely, and the order of magnitude of saving is inversely proportional to target angular speed. We did design two new components of CCD camera. Due to the matured CMOS (Complementary metal-oxide-semiconductor) technology, the on-chip Sample and Hold (SAH) circuitry can be designed for a dual Photon Detector (PD) analog circuitry for changedetection that predicts skipping or going forward at a sufficient sampling frame rate. For an admitted frame, there is a purely random sparse matrix [Φ] which is implemented at each bucket pixel level the charge transport bias voltage toward its neighborhood buckets or not, and if not, it goes to the ground drainage. Since the snapshot image is not a video, we could not apply the usual MPEG video compression and Hoffman entropy codec as well as powerful WaveNet Wrapper on sensor level. We shall compare (i) Pre-Processing FFT and a threshold of significant Fourier mode components and inverse FFT to check PSNR; (ii) Post-Processing image recovery will be selectively done by CDT&D adaptive version of linear programming at L1 minimization and L2 similarity. For (ii) we need to determine in new frames selection by SAH circuitry (i) the degree of information (d.o.i) K(t) dictates the purely random linear sparse combination of measurement data a la [Φ]M,N M(t) = K(t) Log N(t).
The angular momentum of condensations within elephant trunks
Lora, V; Esquivel, A
2009-01-01
The radiation from newly born stars photoevaporates their parental neutral cloud, leading to the formation of dense clumps that will eventually form stars. We present 3D simulations of the interaction of a neutral cloud with an external ionising radiation field, and compute the angular momenta of these collapsing clumps. The angular momenta of these collapsing clumps show that they have preferential orient mostly perpendicular to the direction of the incident ionising photon field. Therefore, the axes of the jet systems that will be eventually ejected (from the star + accretion disk systems that will form) will be oriented approximately perpendicular to the direction to the photoionising source.
Efficient Sorting of Free Electron Orbital Angular Momentum
McMorran, Benjamin J; Lavery, Martin P J
2016-01-01
We propose a method for sorting electrons by orbital angular momentum (OAM). Several methods now exist to prepare electron wavefunctions in OAM states, but no technique has been developed for efficient, parallel measurement of pure and mixed electron OAM states. The proposed technique draws inspiration from the recent demonstration of the sorting of OAM through modal transformation. We show that the same transformation can be performed with electrostatic electron optical elements. Specifically, we show that a charged needle and an array of electrodes perform the transformation and phase correction necessary to sort orbital angular momentum states. This device may enable the analysis of the spatial mode distribution of inelastically scattered electrons.
Continuous Variable Entanglement and Squeezing of Orbital Angular Momentum States
DEFF Research Database (Denmark)
Lassen, Mikael Østergaard; Leuchs, Gerd; Andersen, Ulrik Lund
2009-01-01
We report the first experimental characterization of the first-order continuous variable orbital angular momentum states. Using a spatially nondegenerate optical parametric oscillator (OPO) we produce quadrature entanglement between the two first-order Laguerre-Gauss modes. The family of orbital...... angular momentum modes is mapped on an orbital Poincaré sphere, where the mode's position on the sphere is spanned by the three orbital parameters. Using a nondegenerate OPO we produce squeezing of these parameters, and as an illustration, we reconstruct the “cigar-shaped” uncertainty volume...
Angular Sensitivity of Gated Micro-Channel Plate Framing Cameras
Energy Technology Data Exchange (ETDEWEB)
Landen, O L; Lobban, A; Tutt, T; Bell, P M; Costa, R; Ze, F
2000-07-24
Gated, microchannel-plate-based (MCP) framing cameras have been deployed worldwide for 0.2 - 9 keV x-ray imaging and spectroscopy of transient plasma phenomena. For a variety of spectroscopic and imaging applications, the angular sensitivity of MCPs must be known for correctly interpreting the data. We present systematic measurements of angular sensitivity at discrete relevant photon energies and arbitrary MCP gain. The results can been accurately predicted by using a simple 2D approximation to the 3D MCP geometry and by averaging over all possible photon ray paths.
Alignment of angular velocity sensors for a vestibular prosthesis
Directory of Open Access Journals (Sweden)
DiGiovanna Jack
2012-02-01
Full Text Available Abstract Vestibular prosthetics transmit angular velocities to the nervous system via electrical stimulation. Head-fixed gyroscopes measure angular motion, but the gyroscope coordinate system will not be coincident with the sensory organs the prosthetic replaces. Here we show a simple calibration method to align gyroscope measurements with the anatomical coordinate system. We benchmarked the method with simulated movements and obtain proof-of-concept with one healthy subject. The method was robust to misalignment, required little data, and minimal processing.
Energy and angular momentum of dilaton black holes
Directory of Open Access Journals (Sweden)
Marcelo Samuel Berman
2008-01-01
Full Text Available Dando seguimiento a un art culo previo, revisamos los resultados para la energ a y momento angular de un hoyo negro de Kerr-Newman, y extendemos el c alculo para el caso de un dilaton en rotaci on, obtenido a partir del modelo de Gar nkle et al. (1991, 1992. Mostramos que hay, en lo que se re ere solamente a la energ a y momento angular, una interacci on entre los campos, de forma que, el gravitacional y el electromagn etico pueden ser ocultados por la intensidad del campo escalar.
Angular velocity response of nanoparticles dispersed in liquid crystal
Huang, Pin-Chun; Shih, Wen-Pin
2013-06-01
A hybrid material of nanoparticles dispersed in liquid crystal changed capacitance after spinning beyond threshold angular velocity. Once the centrifugal force of nanoparticles overcomes the attractive force between liquid crystals, the nanoparticles begin to move. The order of highly viscous liquid crystals is disturbed by the nanoparticles' penetrative movement, and the dielectric constant of the liquid crystal cell changes as a result. We found that the angular velocity response of nanoparticles dispersed in liquid crystal with higher working temperature and nanoparticles' density provided higher sensitivity. The obtained results are important for the continuous improvement of liquid-crystal-based inertial sensors or nano-viscometers.
Effect of Orbital Angular Momentum on Nondiffracting Ultrashort Optical Pulses.
Ornigotti, Marco; Conti, Claudio; Szameit, Alexander
2015-09-01
We introduce a new class of nondiffracting optical pulses possessing orbital angular momentum. By generalizing the X-wave solution of the Maxwell equation, we discover the coupling between angular momentum and the temporal degrees of freedom of ultrashort pulses. The spatial twist of propagation invariant light pulse turns out to be directly related to the number of optical cycles. Our results may trigger the development of novel multilevel classical and quantum transmission channels free of dispersion and diffraction. They may also find application in the manipulation of nanostructured objects by ultrashort pulses and for novel approaches to the spatiotemporal measurements in ultrafast photonics.
Four Cases of Angular Cheilitis in Orthodontic Patients
Directory of Open Access Journals (Sweden)
P Kafaie
2006-07-01
Full Text Available Contact dermatitis is an inflammatory reaction of the skin and mucosa to either external or internal factors. It can be divided to two forms of irritant contact dermatitis and allergic contact dermatitis. Nickel is one of the most common materials that causes allergic contact dermatitis and is widely used in orthodontic appliances. The inflammatory reaction to this metal in orthodontics is usually stomatitis and angular cheilitis is very rare. We report 4 cases of angular cheilitis in orthodontic patients and discuss about their causes and treatments.
Egorov, Yu. G.; Kulkov, V. M.; Terentyev, V. V.; Firsyuk, S. O.; Shemyakov, A. O.
2016-11-01
The problem of controlling the angular momentum of spacecraft using magnetic attitude control systems interacting with the Earth's magnetic field is considered. A mathematical model for the angular motion dynamics of a spacecraft has been constructed. An approach to determining the parameters of the control law for a spacecraft attitude control and stabilization system that ensures angular momentum dissipation is proposed.
Astronomy at high angular resolution a compendium of techniques in the visible and near-infrared
Hussain, Gaitee; Berger, Jean-Philippe; Schmidtobreick, Linda
2016-01-01
This book offers an essential compendium of astronomical high-resolution techniques. Recent years have seen considerable developments in such techniques, which are critical to advances in many areas of astronomy. As reflected in the book, these techniques can be divided into direct methods, interferometry, and reconstruction methods, and can be applied to a huge variety of astrophysical systems, ranging from planets, single stars and binaries to active galactic nuclei, providing angular resolution in the micro- to tens of milliarcsecond scales. Written by experts in their fields, the chapters cover adaptive optics, aperture masking imaging, spectra disentangling, interferometry, lucky imaging, Roche tomography, imaging with interferometry, interferometry of AGN, AGN reverberation mapping, Doppler- and magnetic imaging of stellar surfaces, Doppler tomography, eclipse mapping, Stokes imaging, and stellar tomography. This book is intended to enable a next generation of astronomers to apply high-resolution techni...
Spatial perception and adaptive sonar behavior.
Aytekin, Murat; Mao, Beatrice; Moss, Cynthia F
2010-12-01
Bat echolocation is a dynamic behavior that allows for real-time adaptations in the timing and spectro-temporal design of sonar signals in response to a particular task and environment. To enable detailed, quantitative analyses of adaptive sonar behavior, echolocation call design was investigated in big brown bats, trained to rest on a stationary platform and track a tethered mealworm that approached from a starting distance of about 170 cm in the presence of a stationary sonar distracter. The distracter was presented at different angular offsets and distances from the bat. The results of this study show that the distance and the angular offset of the distracter influence sonar vocalization parameters of the big brown bat, Eptesicus fuscus. Specifically, the bat adjusted its call duration to the closer of two objects, distracter or insect target, and the magnitude of the adjustment depended on the angular offset of the distracter. In contrast, the bat consistently adjusted its call rate to the distance of the insect, even when this target was positioned behind the distracter. The results hold implications for understanding spatial information processing and perception by echolocation.
Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development
Chuss, D. T.; Ali, A.; Amiri, M.; Appel, J.; Bennett, C. L.; Colazo, F.; Denis, K. L.; Dünner, R.; Essinger-Hileman, T.; Eimer, J.; Fluxa, P.; Gothe, D.; Halpern, M.; Harrington, K.; Hilton, G.; Hinshaw, G.; Hubmayr, J.; Iuliano, J.; Marriage, T. A.; Miller, N.; Moseley, S. H.; Mumby, G.; Petroff, M.; Reintsema, C.; Rostem, K.; U-Yen, K.; Watts, D.; Wagner, E.; Wollack, E. J.; Xu, Z.; Zeng, L.
2016-08-01
The Cosmology Large Angular Scale Surveyor (CLASS) will measure the polarization of the Cosmic Microwave Background to search for and characterize the polarized signature of inflation. CLASS will operate from the Atacama Desert and observe ˜ 70 % of the sky. A variable-delay polarization modulator provides modulation of the polarization at ˜ 10 Hz to suppress the 1/ f noise of the atmosphere and enable the measurement of the large angular scale polarization modes. The measurement of the inflationary signal across angular scales that spans both the recombination and reionization features allows a test of the predicted shape of the polarized angular power spectra in addition to a measurement of the energy scale of inflation. CLASS is an array of telescopes covering frequencies of 38, 93, 148, and 217 GHz. These frequencies straddle the foreground minimum and thus allow the extraction of foregrounds from the primordial signal. Each focal plane contains feedhorn-coupled transition-edge sensors that simultaneously detect two orthogonal linear polarizations. The use of single-crystal silicon as the dielectric for the on-chip transmission lines enables both high efficiency and uniformity in fabrication. Integrated band definition has been implemented that both controls the bandpass of the single-mode transmission on the chip and prevents stray light from coupling to the detectors.
The Angular Diameter and Fundamental Parameters of Sirius A
Davis, J; North, J R; Robertson, J G; Tango, W J; Tuthill, P G
2010-01-01
The Sydney University Stellar Interferometer (SUSI) has been used to make a new determination of the angular diameter of Sirius A. The observations were made at an effective wavelength of 694.1 nm and the new value for the limb-darkened angular diameter is 6.048 +/- 0.040mas (+/-0.66%). This new result is compared with previous measurements and is found to be in excellent agreement with a conventionally calibrated measurement made with the European Southern Observatory's Very Large Telescope Interferometer (VLTI) at 2.176 microns (but not with a second globally calibrated VLTI measurement). A weighted mean of the SUSI and first VLTI results gives the limb-darkened angular diameter of Sirius A as 6.041 +/- 0.017mas (+/-0.28%). Combination with the Hipparcos parallax gives the radius equal to 1.713 +/- 0.009R_sun. The bolometric flux has been determined from published photometry and spectrophotometry and, combined with the angular diameter, yields the emergent flux at the stellar surface equal to (5.32+/- 0.14)...
Drell-Yan lepton angular distribution at small transverse momentum
Boer, Daniel; Vogelsang, Werner
2006-01-01
We investigate the dependence of the Drell-Yan cross section on lepton polar and azimuthal angles, as generated by the lowest-order QCD annihilation and Compton processes. We focus, in particular, on the azimuthal-angular distributions, which are of the form cos phi and cos2 phi. At small transverse
Demonstrating the Direction of Angular Velocity in Circular Motion
Demircioglu, Salih; Yurumezoglu, Kemal; Isik, Hakan
2015-01-01
Rotational motion is ubiquitous in nature, from astronomical systems to household devices in everyday life to elementary models of atoms. Unlike the tangential velocity vector that represents the instantaneous linear velocity (magnitude and direction), an angular velocity vector is conceptually more challenging for students to grasp. In physics…
Data visualization with D3 and AngularJS
Körner, Christoph
2015-01-01
If you are a web developer with experience in AngularJS and want to implement interactive visualizations using D3.js, this book is for you. Knowledge of SVG or D3.js will give you an edge to get the most out of this book.
Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development
Chuss, D. T.; Ali, A.; Amiri, M.; Appel, J.; Bennett, C. L.; Colazo, F.; Denis, K. L.; Dunner, R.; Essinger-Hileman, T.; Eimer, J.; Fluxa, P.; Gothe, D.; Halpern, M.; Harrington, K.; Hilton, G.; Hinshaw, G.; Hubmayr, J.; Iuliano, J.; Marriage, T. A.; Miller, N.; Moseley, S. H.; Mumby, G.; Petroff, M.; Reintsema, C.; Rostem, K.; U-yen, K.; Watts, D.; Wagner, E.; Wollack, E. J.; Xu, Z.; Zeng, L.
2015-01-01
The Cosmology Large Angular Scale Surveyor (CLASS) will measure the polarization of the Cosmic Microwave Background to search for and characterize the polarized signature of inflation. CLASS will operate from the Atacama Desert and observe approx.70% of the sky. A variable-delay polarization modulator provides modulation of the polarization at approx.10Hz to suppress the 1/f noise of the atmosphere and enable the measurement of the large angular scale polarization modes. The measurement of the inflationary signal across angular scales that spans both the recombination and reionization features allows a test of the predicted shape of the polarized angular power spectra in addition to a measurement of the energy scale of inflation. CLASS is an array of telescopes covering frequencies of 38, 93, 148, and 217 GHz. These frequencies straddle the foreground minimum and thus allow the extraction of foregrounds from the primordial signal. Each focal plane contains feedhorn-coupled transition-edge sensors that simultaneously detect two orthogonal linear polarizations. The use of single-crystal silicon as the dielectric for the on-chip transmission lines enables both high efficiency and uniformity in fabrication. Integrated band definition has been implemented that both controls the bandpass of the single-mode transmission on the chip and prevents stray light from coupling to the detectors.
Low Angular Momentum in Clumpy, Turbulent Disk Galaxies
Obreschkow, Danail; Glazebrook, Karl; Bassett, Robert; Fisher, David B.; Abraham, Roberto G.; Wisnioski, Emily; Green, Andrew W.; McGregor, Peter J.; Damjanov, Ivana; Popping, Attila; Jørgensen, Inger
2015-12-01
We measure the stellar specific angular momentum {j}s={J}s/{M}s in four nearby (z ≈ 0.1) disk galaxies that have stellar masses {M}s near the break {M}s* of the galaxy mass function but look like typical star-forming disks at z ≈ 2 in terms of their low stability (Q ≈ 1), clumpiness, high ionized gas dispersion (40-50 {km} {{{s}}}-1), high molecular gas fraction (20%-30%), and rapid star formation (˜ 20{M}⊙ {{yr}}-1). Combining high-resolution (Keck-OSIRIS) and large-radius (Gemini-GMOS) spectroscopic maps, only available at low z, we discover that these targets have ˜ 3 times less stellar angular momentum than typical local spiral galaxies of equal stellar mass and bulge fraction. Theoretical considerations show that this deficiency in angular momentum is the main cause of their low stability, while the high gas fraction plays a complementary role. Interestingly, the low {j}s values of our targets are similar to those expected in the {M}s* population at higher z from the approximate theoretical scaling {j}s\\propto {(1+z)}-1/2 at fixed {M}s. This suggests that a change in angular momentum, driven by cosmic expansion, is the main cause for the remarkable difference between clumpy {M}s* disks at high z (which likely evolve into early-type galaxies) and mass-matched local spirals.
Remarks on the Total Angular Momentum in General Relativity
Institute of Scientific and Technical Information of China (English)
ZHANG Xiao
2003-01-01
We verify that the total angular momentum 3-vector defined by the author [X. Zhang, Commun. Math.Phys. 206 (1999) 137] is equal to (0, 0, ma) forany time slice in both the Kerr and the Kerr-Newman spacetimes.
Angular correlation of annihilation photons in ice single crystals
DEFF Research Database (Denmark)
Mogensen, O. E.; Kvajic, G.; Eldrup, Morten Mostgaard
1971-01-01
Linear-slit angular-correlation curves were obtained at - 148 °C for the [0001], [10¯10], and [11¯20] directions in single crystals of ice. Besides the narrow central peak, pronounced narrow side peaks were also observed. They occurred at angles θ=2πℏgz/mc, where gz is the projection of reciproca...
Investigation of an angular spectrum approach for pulsed ultrasound fields
DEFF Research Database (Denmark)
Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt
2013-01-01
An Angular Spectrum Approach (ASA)is formulated and employed to simulate linear pulsed ultra sound fields for high bandwidth signals. Ageometrically focused piston transducer is used as the acoustic source. Signals are cross-correlated to findthe true sound speed during the measurement to make th...
Influence of the angular momentum on nuclear fission
Energy Technology Data Exchange (ETDEWEB)
Tanikawa, Masashi [Tokyo Univ. (Japan). Faculty of Science
1996-03-01
The effects of the angular momentum on the mechanism of nuclear fission are studied about the reaction systems of compound nucleus of {sup 210}P and {sup 239}Np by the time-of-flight (TOF) method. The reaction systems in this work are {sup 209}Bi+P, {sup 206}Pb+{alpha}, {sup 206}Po+{alpha}, {sup 198}Pt+{sup 12}C, {sup 238}U+P and {sup 232}Th+{sup 7}Li. Target was prepared by vacuum evaporating of each about 100 {mu}g/cm{sup 2} of {sup 209}Bi, {sup 206}Pb and {sup 198}Pt on 10 {mu}g/cm{sup 2} of carbon film. On compound nucleus {sup 210}Po, {sup 210}Po fissions at Ex=45McV but it fissions after 1 or 2 neutrons emission at higher excited energy (Ex=57 MeV). TKE shows almost the same values except higher value of {sup 209}Bi+P. The decreasing tendency of width of TKE distribution with increasing the angular momentum is found at the first time in this work. The effect of the angular momentum on the fission is small in the case of low angular momentum. On the compound nucleus {sup 239}Np, the effects are shown at the asymmetric fission part of the mass distribution. (S.Y.)
Spin-Orbit Coupling and the Conservation of Angular Momentum
Hnizdo, V.
2012-01-01
In nonrelativistic quantum mechanics, the total (i.e. orbital plus spin) angular momentum of a charged particle with spin that moves in a Coulomb plus spin-orbit-coupling potential is conserved. In a classical nonrelativistic treatment of this problem, in which the Lagrange equations determine the orbital motion and the Thomas equation yields the…
A Historical Discussion of Angular Momentum and its Euler Equation
Sparavigna, Amelia Carolina
2015-01-01
We propose a discussion of angular momentum and its Euler equation, with the aim of giving a short outline of their history. This outline can be useful for teaching purposes too, to amend some problems that students can have in learning this important physical quantity.
Alignment of gold nanorods by angular photothermal depletion
Energy Technology Data Exchange (ETDEWEB)
Taylor, Adam B.; Chow, Timothy T. Y.; Chon, James W. M., E-mail: jchon@swin.edu.au [Centre for Micro-Photonics, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, P.O. Box 218, Hawthorn, 3122 VIC (Australia)
2014-02-24
In this paper, we demonstrate that a high degree of alignment can be imposed upon randomly oriented gold nanorod films by angular photothermal depletion with linearly polarized laser irradiation. The photothermal reshaping of gold nanorods is observed to follow quadratic melting model rather than the threshold melting model, which distorts the angular and spectral hole created on 2D distribution map of nanorods to be an open crater shape. We have accounted these observations to the alignment procedures and demonstrated good agreement between experiment and simulations. The use of multiple laser depletion wavelengths allowed alignment criteria over a large range of aspect ratios, achieving 80% of the rods in the target angular range. We extend the technique to demonstrate post-alignment in a multilayer of randomly oriented gold nanorod films, with arbitrary control of alignment shown across the layers. Photothermal angular depletion alignment of gold nanorods is a simple, promising post-alignment method for creating future 3D or multilayer plasmonic nanorod based devices and structures.
Obtaining the Electron Angular Momentum Coupling Spectroscopic Terms, jj
Orofino, Hugo; Faria, Roberto B.
2010-01-01
A systematic procedure is developed to obtain the electron angular momentum coupling (jj) spectroscopic terms, which is based on building microstates in which each individual electron is placed in a different m[subscript j] "orbital". This approach is similar to that used to obtain the spectroscopic terms under the Russell-Saunders (LS) coupling…
Angular Momentum of Supersymmetric Non-isotropic Traps
Institute of Scientific and Technical Information of China (English)
XU Qiang
2001-01-01
A simple way to explain quantum behavior of supersymmetric non-isotropic traps is proposed in the framework of sermiunitary formulation of supersymmetric quantum mechanics. Using semiunitary formulation we can simultaneously supersymmetrize the complete set of observables, especially including angular moment.
Optical angular momentum conversion in a nanoslit: reply
Chimento, P.F.; Alkemade, P.F.A.; T Hooft, G.W.; Eliel, E.R.
2013-01-01
We respond to a Comment on our Letter [Opt. Lett. 37, 4946 (2012)], in which we reported on the spin-to-orbital optical angular momentum conversion of a circular nanoslit in a thin metal layer. We claimed, in an unfortunately worded sentence, that the conversion efficiency was independent of the sli
Generation of the Stigmatic Beam with Orbital Angular Momentum
Institute of Scientific and Technical Information of China (English)
高春清; 魏光辉; Horst WEBER
2001-01-01
The stigmatic beam with orbital angular momentum is generated by transforming the Hermite-Gaussian beamof a diode-pumped Nd:YAG laser through a rotated cylindrical optical system. Behind the transformation optics,the output beam has an intensity distribution of ring shape and a twist phase. The beam transformation istheoretically calculated and the result has been confirmed in the experiments.
The operator method for angular momentum and SU3
Eekelen, H.A.M. van; Ruijgrok, Th.W.
1966-01-01
It is well known how Schwinger's1) operator method can be used to construct all representations of the angular momentum operators. We give a brief account of this method and show that it is very convenient for a short derivation of the general Clebsch-Gordan coefficients. The method is then applied
Energy and linear and angular momenta in simple electromagnetic systems
Mansuripur, Masud
2015-01-01
We present examples of simple electromagnetic systems in which energy, linear momentum, and angular momentum exhibit interesting behavior. The systems are sufficiently simple to allow exact solutions of Maxwell's equations in conjunction with the electrodynamic laws of force, torque, energy, and momentum. In all the cases examined, conservation of energy and momentum is confirmed.
Long-time tails in angular momentum correlations
Lowe, C.P.; Frenkel, D.; Masters, A.J.
1995-01-01
We compare computer simulation results for the angular velocity autocorrelation function (AVACF) of a colloidal particle with theoretical predictions. We consider both spherical and nonspherical particles in two and three dimensions. The theoretical prediction for the long-time decay of the AVACF in
Estimating Discrete Power Angular Spectra in Multiprobe OTA Setups
DEFF Research Database (Denmark)
Fan, Wei; Nielsen, Jesper Ødum; Pedersen, Gert Frølund
2014-01-01
The letter discusses over-the-air (OTA) testing for multiple-input–multiple-output (MIMO) capable terminals with emphasis on estimating discrete power angular spectrum modeled at the receiver (Rx) side in the test zone. Two techniques based on a uniform circular array (UCA) are proposed to obtain...
Angular cheilitis: a case for the oral physician?
Williams, M
1995-03-01
It has been suggested that in the future the role of the dental practitioner increasingly will be that of the oral physician. This case report describes the difficulties encountered by a general dental practitioner while investigating and treating a patient with angular cheilitis.
Exact angular momentum projection based on cranked HFB solution
Energy Technology Data Exchange (ETDEWEB)
Enami, Kenichi; Tanabe, Kosai; Yosinaga, Naotaka [Saitama Univ., Urawa (Japan). Dept. of Physics
1998-03-01
Exact angular momentum projection of cranked HFB solutions is carried out. It is reconfirmed from this calculation that cranked HFB solutions reproduce the intrinsic structure of deformed nucleus. The result also indicates that the energy correction from projection is important for further investigation of nuclear structure. (author)
Angular momentum projection of tilted axis rotating states
Energy Technology Data Exchange (ETDEWEB)
Oi, M.; Onishi, N.; Tajima, N. [Tokyo Univ. (Japan); Horibata, T.
1998-03-01
We applied an exact angular momentum projection to three dimensional cranked HFB (3d-CHFB) states. Tilted axis rotating states (TAR) and principal axis rotating states (PAR) are compared. It is shown that TAR is more adequate than PAR for description of the back bending phenomena driven by tilted rotation or wobbling motion. (author)
Directory of Open Access Journals (Sweden)
Paul Rozin
2008-02-01
Full Text Available People live in a world in which they are surrounded by potential disgust elicitors such as ``used'' chairs, air, silverware, and money as well as excretory activities. People function in this world by ignoring most of these, by active avoidance, reframing, or adaptation. The issue is particularly striking for professions, such as morticians, surgeons, or sanitation workers, in which there is frequent contact with major disgust elicitors. In this study, we study the ``adaptation'' process to dead bodies as disgust elicitors, by measuring specific types of disgust sensitivity in medical students before and after they have spent a few months dissecting a cadaver. Using the Disgust Scale, we find a significant reduction in disgust responses to death and body envelope violation elicitors, but no significant change in any other specific type of disgust. There is a clear reduction in discomfort at touching a cold dead body, but not in touching a human body which is still warm after death.
Energy Technology Data Exchange (ETDEWEB)
Huq, Saleemul
2011-11-15
Efforts to help the world's poor will face crises in coming decades as climate change radically alters conditions. Action Research for Community Adapation in Bangladesh (ARCAB) is an action-research programme on responding to climate change impacts through community-based adaptation. Set in Bangladesh at 20 sites that are vulnerable to floods, droughts, cyclones and sea level rise, ARCAB will follow impacts and adaptation as they evolve over half a century or more. National and international 'research partners', collaborating with ten NGO 'action partners' with global reach, seek knowledge and solutions applicable worldwide. After a year setting up ARCAB, we share lessons on the programme's design and move into our first research cycle.
Simplified Generation of High-Angular-Momentum Light Beams
Savchenkov, Anatoliy; Maleki, Lute; Matsko, Andrey; Strekalov, Dmitry; Grudinin, Ivan
2007-01-01
A simplified method of generating a beam of light having a relatively high value of angular momentum (see figure) involves the use of a compact apparatus consisting mainly of a laser, a whispering- gallery-mode (WGM) resonator, and optical fibers. The method also can be used to generate a Bessel beam. ( Bessel beam denotes a member of a class of non-diffracting beams, so named because their amplitudes are proportional to Bessel functions of the radii from their central axes. High-order Bessel beams can have high values of angular momentum.) High-angular-momentum light beams are used in some applications in biology and nanotechnology, wherein they are known for their ability to apply torque to make microscopic objects rotate. High-angular-momentum light beams could also be used to increase bandwidths of fiber-optic communication systems. The present simplified method of generating a high-angular-momentum light beam was conceived as an alternative to prior such methods, which are complicated and require optical setups that include, variously, holograms, modulating Fabry-Perot cavities, or special microstructures. The present simplified method exploits a combination of the complex structure of the electromagnetic field inside a WGM resonator, total internal reflection in the WGM resonator, and the electromagnetic modes supported by an optical fiber. The optical fiber used to extract light from the WGM resonator is made of fused quartz. The output end of this fiber is polished flat and perpendicular to the fiber axis. The input end of this fiber is cut on a slant and placed very close to the WGM resonator at an appropriate position and orientation. To excite the resonant whispering- gallery modes, light is introduced into the WGM resonator via another optical fiber that is part of a pigtailed fiber-optic coupler. Light extracted from the WGM resonator is transformed into a high-angular- momentum beam inside the extraction optical fiber and this beam is emitted from the
Power calculation of linear and angular incremental encoders
Prokofev, Aleksandr V.; Timofeev, Aleksandr N.; Mednikov, Sergey V.; Sycheva, Elena A.
2016-04-01
Automation technology is constantly expanding its role in improving the efficiency of manufacturing and testing processes in all branches of industry. More than ever before, the mechanical movements of linear slides, rotary tables, robot arms, actuators, etc. are numerically controlled. Linear and angular incremental photoelectric encoders measure mechanical motion and transmit the measured values back to the control unit. The capabilities of these systems are undergoing continual development in terms of their resolution, accuracy and reliability, their measuring ranges, and maximum speeds. This article discusses the method of power calculation of linear and angular incremental photoelectric encoders, to find the optimum parameters for its components, such as light emitters, photo-detectors, linear and angular scales, optical components etc. It analyzes methods and devices that permit high resolutions in the order of 0.001 mm or 0.001°, as well as large measuring lengths of over 100 mm. In linear and angular incremental photoelectric encoders optical beam is usually formulated by a condenser lens passes through the measuring unit changes its value depending on the movement of a scanning head or measuring raster. Past light beam is converting into an electrical signal by the photo-detecter's block for processing in the electrical block. Therefore, for calculating the energy source is a value of the desired value of the optical signal at the input of the photo-detecter's block, which reliably recorded and processed in the electronic unit of linear and angular incremental optoelectronic encoders. Automation technology is constantly expanding its role in improving the efficiency of manufacturing and testing processes in all branches of industry. More than ever before, the mechanical movements of linear slides, rotary tables, robot arms, actuators, etc. are numerically controlled. Linear and angular incremental photoelectric encoders measure mechanical motion and
The role of angular momentum conservation law in statistical mechanics
Directory of Open Access Journals (Sweden)
I.M. Dubrovskii
2008-12-01
Full Text Available Within the limits of Khinchin ideas [A.Y. Khinchin, Mathematical Foundation of Statistical Mechanics. NY, Ed. Dover, 1949] the importance of momentum and angular momentum conservation laws was analyzed for two cases: for uniform magnetic field and when magnetic field is absent. The law of momentum conservation does not change the density of probability distribution in both cases, just as it is assumed in the conventional theory. It is shown that in systems where the kinetic energy depends only on particle momenta canonically conjugated with Cartesian coordinates being their diagonal quadric form,the angular momentum conservation law changes the density of distribution of the system only in case the full angular momentum of a system is not equal to zero. In the gas of charged particles in a uniform magnetic field the density of distribution also varies if the angular momentum is zero [see Dubrovskii I.M., Condensed Matter Physics, 2206, 9, 23]. Two-dimensional gas of charged particles located within a section of an endless strip filled with gas in magnetic field is considered. Under such conditions the angular momentum is not conserved. Directional particle flows take place close to the strip boundaries, and, as a consequence, the phase trajectory of the considered set of particles does not remain within the limited volume of the phase space. In order to apply a statistical thermodynamics method, it was suggested to consider near-boundary trajectories relative to a reference system that moves uniformly. It was shown that if the diameter of an orbit having average thermal energy is much smaller than a strip width, the corrections to thermodynamic functions are small depending on magnetic field. Only the average velocity of near-boundary particles that form near-boundary electric currents creating the paramagnetic moment turn out to be essential.
Helicon modes in uniform plasmas. III. Angular momentum
Energy Technology Data Exchange (ETDEWEB)
Stenzel, R. L.; Urrutia, J. M. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States)
2015-09-15
Helicons are electromagnetic waves with helical phase fronts propagating in the whistler mode in magnetized plasmas and solids. They have similar properties to electromagnetic waves with angular momentum in free space. Helicons are circularly polarized waves carrying spin angular momentum and orbital angular momentum due to their propagation around the ambient magnetic field B{sub 0}. These properties have not been considered in the community of researchers working on helicon plasma sources, but are the topic of the present work. The present work focuses on the field topology of helicons in unbounded plasmas, not on helicon source physics. Helicons are excited in a large uniform laboratory plasma with a magnetic loop antenna whose dipole axis is aligned along or across B{sub 0}. The wave fields are measured in orthogonal planes and extended to three dimensions (3D) by interpolation. Since density and B{sub 0} are uniform, small amplitude waves from loops at different locations can be superimposed to generate complex antenna patterns. With a circular array of phase shifted loops, whistler modes with angular and axial wave propagation, i.e., helicons, are generated. Without boundaries radial propagation also arises. The azimuthal mode number m can be positive or negative while the field polarization remains right-hand circular. The conservation of energy and momentum implies that these field quantities are transferred to matter which causes damping or reflection. Wave-particle interactions with fast electrons are possible by Doppler shifted resonances. The transverse Doppler shift is demonstrated. Wave-wave interactions are also shown by showing collisions between different helicons. Whistler turbulence does not always have to be created by nonlinear wave-interactions but can also be a linear superposition of waves from random sources. In helicon collisions, the linear and/or orbital angular momenta can be canceled, which results in a great variety of field
ADAPTIVE ELLIPSOIDAL ACOUSTIC INFINITE ELEMENT
Institute of Scientific and Technical Information of China (English)
Yang Ruiliang; Wang Hongzhen
2004-01-01
It is shown that the basis of the ellipsoidal acoustic infinite element Burnett method,the multipole expansion,cannot represent real ellipsoidal acoustic field exactly.To solve the problem,a weight of angular direction is added to the multipole expansion.The comparison of the modified method and the prime method shows that the modified method can describe and solve the ellipsoidal acoustic field more accurately than ever.A dilating sphere is used to test the new method further.Unlike other infinite element methods,varied ratio of the ellipsoidal artificial boundary instead of sphere is used.The pressure value of the artificial boundary is utilized as the initial value of the new method.Then the radiating phenomena of the ellipsoidal acoustic field can be researched using the new method.These examples show the feasibility of the adaptive method.
Yu, Haohai; Zhang, Huaijin; Wang, Yicheng; Han, Shuo; Yang, Haifang; Xu, Xiangang; Wang, Zhengping; Petrov, V; Wang, Jiyang
2013-11-12
We demonstrate the optical orbital angular momentum conservation during the transfer process from subwavelength plasmonic vortex lens (PVLs) to light and the generating process of surface plasmon polaritons (SPPs). Illuminating plasmonic vortex lenses with beams carrying optical orbital angular momentum, the SP vortices with orbital angular momentum were generated and inherit the optical angular momentum of light beams and PVLs. The angular momentum of twisting SP electromagnetic field is tunable by the twisted metal/dielectric interfaces of PVLs and angular momentum of illuminating singular light. This work may open the door for several possible applications of SP vortices in subwavelength region.
Fission fragment angular distributions in pre-actinide nuclei
Banerjee, Tathagata; Nath, S.; Jhingan, A.; Kaur, Gurpreet; Dubey, R.; Yadav, Abhishek; Laveen, P. V.; Shamlath, A.; Shareef, M.; Gehlot, J.; Saneesh, N.; Prasad, E.; Sugathan, P.; Pal, Santanu
2016-10-01
Background: Complete fusion of two nuclei leading to formation of a heavy compound nucleus (CN) is known to be hindered by various fission-like processes, in which the composite system reseparates after capture of the target and the projectile inside the potential barrier. As a consequence of these non-CN fission (NCNF) processes, fusion probability (PCN) starts deviating from unity. Despite substantial progress in understanding, the onset and the experimental signatures of NCNF and the degree of its influence on fusion have not yet been unambiguously identified. Purpose: This work aims to investigate the presence of NCNF, if any, in pre-actinide nuclei by systematic study of fission angular anisotropies and fission cross sections (σfis) in a number of nuclear reactions carried out at and above the Coulomb barrier (VB) . Method: Fission fragment angular distributions were measured for six 28Si-induced reactions involving isotopically enriched targets of 169Tm,176Yb,175Lu,180Hf,181Ta, and 182W leading to probable formation of CN in the pre-actinide region, at a laboratory energy (Elab) range of 129-146 MeV. Measurements were performed with large angular coverage (θlab=41∘ -170∘) in which fission fragments (FFs) were detected by nine hybrid telescope (E -Δ E ) detectors. Extracted fission angular anisotropies and σfis were compared with statistical model (SM) predictions. Results: Barring two reactions involving targets with large non-zero ground state spin (J ) , viz., 175Lu(7/2+) and 181Ta(7/2+) , experimental fission angular anisotropies were found to be higher in comparison with predictions of the statistical saddle point model (SSPM), at Ec .m . near VB. Comparison of present results with those from neighboring systems revealed that experimental anisotropies increasingly deviated from SSPM predictions as one moved from pre-actinide to actinide nuclei. For reactions involving targets with large nonzero J , this deviation was subdued. Comparison between
Digital Repository Service at National Institute of Oceanography (India)
Chakraborty, B.; Kodagali, V.N.; Baracho, J.
-consuming sea-floor exploration for offshore geological sampling purposes, a real-time classification approach is of paramount importance. Since ANN has the inherent nature of nonparametric learning, these techniques may have the potential for equal adaptation... scatter plot with respect to the incidence angles. Utilizing the sea-floor slopes, the beam angles are converted to incidence angles. The corrected backscattering strength values (in decibels) for each beam are binned in equal angular bins of 1 intervals...
Angular dependence of Wigner time delay: Relativistic Effects
Mandal, A.; Deshmukh, P. C.; Manson, S. T.; Kkeifets, A. S.
2016-05-01
Laser assisted photoionization time delay mainly consists of two parts: Wigner time delay, and time delay in continuum-continuum transition. Wigner time delay results from the energy derivative of the phase of the photoionization amplitude (matrix element). In general, the photoionization time delay is not the same in all directions relative to the incident photon polarization, although when a single transition dominates the amplitude, the resultant time delay is essentially isotropic. The relativistic-random-phase approximation is employed to determine the Wigner time delay in photoionization from the outer np subshells of the noble gas atoms, Ne through Xe. The time delay is found to significantly depend on angle, as well as energy. The angular dependence of the time delay is found to be quite sensitive to atomic dynamics and relativistic effects, and exhibit strong energy and angular variation in the neighborhood of Cooper minima. Work supported by DOE, Office of Chemical Sciences and DST (India).
Efficient separation of the orbital angular momentum eigenstates of light.
Mirhosseini, Mohammad; Malik, Mehul; Shi, Zhimin; Boyd, Robert W
2013-01-01
Orbital angular momentum (OAM) of light is an attractive degree of freedom for fundamental studies in quantum mechanics. In addition, the discrete unbounded state-space of OAM has been used to enhance classical and quantum communications. Unambiguous measurement of OAM is a key part of all such experiments. However, state-of-the-art methods for separating single photons carrying a large number of different OAM values are limited to a theoretical separation efficiency of about 77%. Here we demonstrate a method which uses a series of unitary optical transformations to enable the measurement of light's OAM with an experimental separation efficiency of >92%. Furthermore, we demonstrate the separation of modes in the angular position basis, which is mutually unbiased with respect to the OAM basis. The high degree of certainty achieved by our method makes it particularly attractive for enhancing the information capacity of multi-level quantum cryptography systems.
Scalable orbital-angular-momentum sorting without destroying photon states
Wang, Fang-Xiang; Yin, Zhen-Qiang; Wang, Shuang; Guo, Guang-Can; Han, Zheng-Fu
2016-01-01
Single photons with orbital angular momentum (OAM) have attracted substantial attention from researchers. A single photon can carry infinite OAM values theoretically. Thus, OAM photon states have been widely used in quantum information and fundamental quantum mechanics. Although there have been many methods for sorting quantum states with different OAM values, the nondestructive and efficient sorter of high-dimensional OAM remains a fundamental challenge. Here, we propose a scalable OAM sorter which can categorize different OAM states simultaneously, meanwhile, preserving both OAM and spin angular momentum. Fundamental elements of the sorter are composed of symmetric multiport beam splitters (BSs) and Dove prisms with cascading structure, which in principle can be flexibly and effectively combined to sort arbitrarily high-dimensional OAM photons. The scalable structures proposed here greatly reduce the number of BSs required for sorting high-dimensional OAMstates. In view of the nondestructive and extensible ...
Angular output of hollow, metal-lined, waveguide Raman sensors
Energy Technology Data Exchange (ETDEWEB)
Biedrzycki, Stephen; Buric, Michael P.; Falk, Joel; Woodruff, Steven D.
2012-04-20
Hollow, metal-lined waveguides used as gas sensors based on spontaneous Raman scattering are capable of large angular collection. The collection of light from a large solid angle implies the collection of a large number of waveguide modes. An accurate estimation of the propagation losses for these modes is required to predict the total collected Raman power. We report a theory/experimental comparison of the Raman power collected as a function of the solid angle and waveguide length. New theoretical observations are compared with previous theory appropriate only for low-order modes. A cutback experiment is demonstrated to verify the validity of either theory. The angular distribution of Raman light is measured using aluminum and silver-lined waveguides of varying lengths.
Angular Momentum Transport in Quasi-Keplerian Accretion Disks
Indian Academy of Sciences (India)
Prasad Subramanian; B. S. Pujari; Peter A. Becker
2004-03-01
We reexamine arguments advanced by Hayashi & Matsuda (2001), who claim that several simple, physically motivated derivations based on mean free path theory for calculating the viscous torque in a quasi-Keplerian accretion disk yield results that are inconsistent with the generally accepted model. If correct, the ideas proposed by Hayashi & Matsuda would radically alter our understanding of the nature of the angular momentum transport in the disk, which is a central feature of accretion disk theory. However, in this paper we point out several fallacies in their arguments and show that there indeed exists a simple derivation based on mean free path theory that yields an expression for the viscous torque that is proportional to the radial derivative of the angular velocity in the accretion disk, as expected. The derivation is based on the analysis of the epicyclic motion of gas parcels in adjacent eddies in the disk.
Time and "angular" dependent backgrounds from stationary axisymmetric solutions
Obregón, O; Ryan, M P; Obregon, Octavio; Quevedo, Hernando; Ryan, Michael P.
2004-01-01
Backgrounds depending on time and on "angular" variable, namely polarized and unpolarized $S^1 \\times S^2$ Gowdy models, are generated as the sector inside the horizons of the manifold corresponding to axisymmetric solutions. As is known, an analytical continuation of ordinary $D$-branes, $iD$-branes allows one to find $S$-brane solutions. Simple models have been constructed by means of analytic continuation of the Schwarzchild and the Kerr metrics. The possibility of studying the $i$-Gowdy models obtained here is outlined with an eye toward seeing if they could represent some kind of generalized $S$-branes depending not only on time but also on an ``angular'' variable.
Efficient polarization of high-angular-momentum systems
Rochester, Simon; Raizen, Mark; Pustelny, Szymon; Auzinsh, Marcis; Budker, Dmitry
2016-01-01
We propose methods of optical pumping that are applicable to open, high-angular-momentum transitions in atoms and molecules, for which conventional optical pumping would lead to significant population loss. Instead of applying circularly polarized cw light, as in conventional optical pumping, we propose to use techniques for coherent population transfer (e.g., adiabatic fast passage) to arrange the atoms so as to increase the entropy removed from the system with each spontaneous decay from the upper state. This minimizes the number of spontaneous-emission events required to produce a stretched state, thus reducing the population loss due to decay to other states. To produce a stretched state in a manifold with angular momentum J, conventional optical pumping requires about 2J spontaneous decays per atom; one of our proposed methods reduces this to about log_2(2J), while another of the methods reduces it to about one spontaneous decay, independent of J.
Higher signal harmonics, LISA's angular resolution and dark energy
Arun, K G; Sathyaprakash, B S; Sinha, Siddhartha; Broeck, Chris Van Den
2007-01-01
It is generally believed that the angular resolution of the Laser Interferometer Space Antenna (LISA) for binary supermassive black holes (SMBH) will not be good enough to identify the host galaxy or galaxy cluster. This conclusion, based on using only the dominant harmonic of the binary SMBH signal, changes dramatically when higher signal harmonics are included in assessing the parameter estimation problem. We show that in a subset of the source parameter space the angular resolution increases by more than a factor of 10, thereby making it possible for LISA to identify the host galaxy/galaxy cluster. Thus, LISA's observation of certain binary SMBH coalescence events could constrain the dark energy equation of state to within a few percent, comparable to the level expected from other dark energy missions.
Angular line scanning deflectometry using a laser pico projector
Zhan, Hao-Xun; Liang, Chao-Wen; Chien, Shih-Che
2016-08-01
In our previous publications, we had successfully made a deflectometry measurement by using a portable laser projector. In this research, we propose the beam weighting centroid method rather than previous the phase shifting method for quantification of the angular direction of the testing beam in the tested optics entrance pupil. By projecting the angular sequential lines on tested optics entrance pupil, the wavefront aberration is reconstructed from two orthogonal directions measurements, in a similar way to the line scanning deflectometry. The limited gray scale problem of laser projector during the phase shifting measurement is therefore eliminated. The reconstructed wavefront is proven to yield a more accurate result than the phase shifting methods at the cost of more image frames and acquisition time.
Atmosphere-earth angular momentum exchange and ENSO cycle
Institute of Scientific and Technical Information of China (English)
钱维宏; 丑纪范
1996-01-01
The time series of the earth’s rotation rate, eastern equatorial Pacific sea surface temperature (Tss), sea level pressure (Psl) and atmospheric angular momentum (Maa) during 1976 -1989 are used to study the relation between atmosphere-earth angular momentum exchange and ENSO cycle. The result shows that (i) there are synergetic relationships among the variations of solid earth’s rotation, eastern equatorial Pacific T,, Psl, different latitude zonal Maa and global Maa; (ii) local atmosphere-ocean interaction over low-latitude area can form ENSO-like cycle through Hadley circulation; (iii) the solid earth and global atmosphere-ocean interaction can form some aperiodic behavior and asynchronous oscillations by mountain torque and earth spin anomalous friction torque acting on each component of solid earth-ocean-atmosphere system; and (iv) actual ENSO cycle is a phenomenon reflecting in Pacific basin through interaction among solid earth, global ocean and the atmosphere.
Angular-dependent magnetization reversal processes in artificial spin ice
Burn, D. M.; Chadha, M.; Branford, W. R.
2015-12-01
The angular dependence of the magnetization reversal in interconnected kagome artificial spin ice structures has been studied through experimental MOKE measurements and micromagnetic simulations. This reversal is mediated by the propagation of magnetic domain walls along the interconnecting bars, which either nucleate at the vertex or arrive following an interaction in a neighboring vertex. The physical differences in these processes show a distinct angular dependence allowing the different contributions to be identified. The configuration of the initial magnetization state, either locally or on a full sublattice of the system, controls the reversal characteristics of the array within a certain field window. This shows how the available magnetization reversal routes can be manipulated and the system can be trained.
Angular diameter distances reconsidered in the Newman and Penrose formalism
Kling, Thomas P
2016-01-01
Using the Newman and Penrose spin coefficient (NP) formalism, we provide a derivation of the Dyer-Roeder equation for the angular diameter distance in cosmological space-times. We show that the geodesic deviation equation written in NP formalism is precisely the Dyer-Roeder equation for a general Friedman-Robertson-Walker (FRW) space-time, and then we examine the angular diameter distance to redshift relation in the case that a flat FRW metric is perturbed by a gravitational potential. We examine the perturbation in the case that the gravitational potential exhibits the properties of a thin gravitational lens, demonstrating how the weak lensing shear and convergence act as source terms for the perturbed Dyer-Roeder equation.
Photonic-phononic orbital angular momentum in Brillouin parametric conversion
Zhu, Zhihan; Mu, Chunyuan; Li, Hongwei
2014-01-01
Orbital angular momentum (OAM) is a fundamental photonic degree of freedom, showed by Allen and co-workers. Its most attractive feature is an inherently infinite dimensionality, which in recent years has obtained several ground-breaking demonstrations for high information-density communication and processing, both in classical and quantum. Here, by seeking the reason for photonic OAM non-conservation in stimulated Brillouin amplification, we report the first demonstration of the evolution law for OAM in Brillouin process. The parameter of OAM can conveniently transfer between the phonons and different polarized photons due to the photonic spin angular momentum conservation. Our results have revealed a parametric conversion mechanism of Brillouin process for Photonic-phononic OAM, demonstrated the role of phononic OAM and the vortex acoustic wave in this process, and suggested this mechanism may find important applications in OAM-based information communication and processing.
Angular Momentum Transport via Internal Gravity Waves in Evolving Stars
Fuller, Jim; Cantiello, Matteo; Brown, Ben
2014-01-01
Recent asteroseismic advances have allowed for direct measurements of the internal rotation rates of many sub-giant and red giant stars. Unlike the nearly rigidly rotating Sun, these evolved stars contain radiative cores that spin faster than their overlying convective envelopes, but slower than they would in the absence of internal angular momentum transport. We investigate the role of internal gravity waves in angular momentum transport in evolving low mass stars. In agreement with previous results, we find that convectively excited gravity waves can prevent the development of strong differential rotation in the radiative cores of Sun-like stars. As stars evolve into sub-giants, however, low frequency gravity waves become strongly attenuated and cannot propagate below the hydrogen burning shell, allowing the spin of the core to decouple from the convective envelope. This decoupling occurs at the base of the sub-giant branch when stars have surface temperatures of roughly 5500 K. However, gravity waves can s...
Investigating pointing tasks across angularly coupled display areas
DEFF Research Database (Denmark)
Hennecke, Fabian; De Luca, Alexander; Nguyen, Ngo Dieu Huong;
2013-01-01
Pointing tasks are a crucial part of today’s graphical user interfaces. They are well understood for flat displays and most prominently are modeled through Fitts’ Law. For novel displays (e.g., curved displays with multi-purpose areas), however, it remains unclear whether such models for predicting...... that the target position affects overall pointing speed and offset in both conditions. However, we also found that Fitts’ Law can in fact still be used to predict performance as on flat displays. Our results help designers to optimize user interfaces on angularly coupled displays when pointing tasks are involved....... user performance still hold – in particular when pointing is performed across differently oriented areas. To answer this question, we conducted an experiment on an angularly coupled display – the Curve – with two input conditions: direct touch and indirect mouse pointer. Our findings show...
Nanoparticles at liquid interfaces: Rotational dynamics and angular locking
Energy Technology Data Exchange (ETDEWEB)
Razavi, Sepideh; Kretzschmar, Ilona [Department of Chemical Engineering, City College of City University of New York, New York, New York 10031 (United States); Koplik, Joel [Department of Physics and The Benjamin Levich Institute for Physico-chemical Hydrodynamics, City College of City University of New York, New York, New York 10031 (United States); Colosqui, Carlos E., E-mail: carlos.colosqui@stonybrook.edu [Department of Mechanical Engineering, Stony Brook University, Stony Brook, New York 11794 (United States)
2014-01-07
Nanoparticles with different surface morphologies that straddle the interface between two immiscible liquids are studied via molecular dynamics simulations. The methodology employed allows us to compute the interfacial free energy at different angular orientations of the nanoparticle. Due to their atomistic nature, the studied nanoparticles present both microscale and macroscale geometrical features and cannot be accurately modeled as a perfectly smooth body (e.g., spheres and cylinders). Under certain physical conditions, microscale features can produce free energy barriers that are much larger than the thermal energy of the surrounding media. The presence of these energy barriers can effectively “lock” the particle at specific angular orientations with respect to the liquid-liquid interface. This work provides new insights on the rotational dynamics of Brownian particles at liquid interfaces and suggests possible strategies to exploit the effects of microscale features with given geometric characteristics.
Angular momentum and torque described with the complex octonion
Weng, Zi-Hua
2015-01-01
The paper aims to adopt the complex octonion to formulate the angular momentum, torque, and force etc in the electromagnetic and gravitational fields. Applying the octonionic representation enables one single definition of angular momentum (or torque, force) to combine some physics contents, which were considered to be independent of each other in the past. J. C. Maxwell used simultaneously two methods, the vector terminology and quaternion analysis, to depict the electromagnetic theory. It motivates the paper to introduce the quaternion space into the field theory, describing the physical feature of electromagnetic and gravitational fields. The spaces of two fields can be chosen as the quaternion spaces, while the coordinate component of quaternion space is able to be the complex number. The quaternion space of electromagnetic field is independent of that of gravitational field. These two quaternion spaces may compose one octonion space. Contrarily, one octonion space can be separated into two subspaces, the...
Angular distribution and atomic effects in condensed phase photoelectron spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Davis, R.F.
1981-11-01
A general concept of condensed phase photoelectron spectroscopy is that angular distribution and atomic effects in the photoemission intensity are determined by different mechanisms, the former being determined largely by ordering phenomena such as crystal momentum conservation and photoelectron diffraction while the latter are manifested in the total (angle-integrated) cross section. In this work, the physics of the photoemission process is investigated in several very different experiments to elucidate the mechanisms of, and correlation between, atomic and angular distribution effects. Theoretical models are discussed and the connection betweeen the two effects is clearly established. The remainder of this thesis, which describes experiments utilizing both angle-resolved and angle-integrated photoemission in conjunction with synchrotron radiation in the energy range 6 eV less than or equal to h ..nu.. less than or equal to 360 eV and laboratory sources, is divided into three parts.
Optomechanics based on angular momentum exchange between light and matter
Shi, H.; Bhattacharya, M.
2016-08-01
The subject of optomechanics involves interactions between optical and mechanical degrees of freedom, and is currently of great interest as an enabler of fundamental investigations in quantum mechanics, as well as a platform for ultrasensitive measurement devices. The majority of optomechanical configurations rely on the exchange of linear momentum between light and matter. We will begin this tutorial with a brief description of such systems. Subsequently, we will introduce optomechanical systems based on angular momentum exchange. In this context, optical fields carrying polarization and orbital angular momentum will be considered, while for the mechanics, torsional and free rotational motion will be of relevance. Our overall aims will be to supply basic analyses of some of the existing theoretical proposals, to provide functional descriptions of some of the experiments conducted thus far, and to consider some directions for future research. We hope this tutorial will be useful to both theorists and experimentalists interested in the subject.
Resolving enantiomers using the optical angular momentum of twisted light.
Brullot, Ward; Vanbel, Maarten K; Swusten, Tom; Verbiest, Thierry
2016-03-01
Circular dichroism and optical rotation are crucial for the characterization of chiral molecules and are of importance to the study of pharmaceutical drugs, proteins, DNA, and many others. These techniques are based on the different interactions of enantiomers with circularly polarized components of plane wave light that carries spin angular momentum (SAM). For light carrying orbital angular momentum (OAM), for example, twisted or helical light, the consensus is that it cannot engage with the chirality of a molecular system as previous studies failed to demonstrate an interaction between optical OAM and chiral molecules. Using unique nanoparticle aggregates, we prove that optical OAM can engage with materials' chirality and discriminate between enantiomers. Further, theoretical results show that compared to circular dichroism, mainly based on magnetic dipole contributions, the OAM analog helical dichroism (HD) is critically dependent on fundamentally different chiral electric quadrupole contributions. Our work opens new venues to study chirality and can find application in sensing and chiral spectroscopy.
Unveiling pseudospin and angular momentum in photonic graphene.
Song, Daohong; Paltoglou, Vassilis; Liu, Sheng; Zhu, Yi; Gallardo, Daniel; Tang, Liqin; Xu, Jingjun; Ablowitz, Mark; Efremidis, Nikolaos K; Chen, Zhigang
2015-02-17
Pseudospin, an additional degree of freedom inherent in graphene, plays a key role in understanding many fundamental phenomena such as the anomalous quantum Hall effect, electron chirality and Klein paradox. Unlike the electron spin, the pseudospin was traditionally considered as an unmeasurable quantity, immune to Stern-Gerlach-type experiments. Recently, however, it has been suggested that graphene pseudospin is a real angular momentum that might manifest itself as an observable quantity, but so far direct tests of such a momentum remained unfruitful. Here, by selective excitation of two sublattices of an artificial photonic graphene, we demonstrate pseudospin-mediated vortex generation and topological charge flipping in otherwise uniform optical beams with Bloch momentum traversing through the Dirac points. Corroborated by numerical solutions of the linear massless Dirac-Weyl equation, we show that pseudospin can turn into orbital angular momentum completely, thus upholding the belief that pseudospin is not merely for theoretical elegance but rather physically measurable.
Resilience of hybrid optical angular momentum qubits to turbulence.
Farías, Osvaldo Jiménez; D'Ambrosio, Vincenzo; Taballione, Caterina; Bisesto, Fabrizio; Slussarenko, Sergei; Aolita, Leandro; Marrucci, Lorenzo; Walborn, Stephen P; Sciarrino, Fabio
2015-02-12
Recent schemes to encode quantum information into the total angular momentum of light, defining rotation-invariant hybrid qubits composed of the polarization and orbital angular momentum degrees of freedom, present interesting applications for quantum information technology. However, there remains the question as to how detrimental effects such as random spatial perturbations affect these encodings. Here, we demonstrate that alignment-free quantum communication through a turbulent channel based on hybrid qubits can be achieved with unit transmission fidelity. In our experiment, alignment-free qubits are produced with q-plates and sent through a homemade turbulence chamber. The decoding procedure, also realized with q-plates, relies on both degrees of freedom and renders an intrinsic error-filtering mechanism that maps errors into losses.
The angular diameter and distance of the Cepheid Zeta Geminorum
Kervella, P; Perrin, G; Schöller, M; Traub, W A; Lacasse, M D
2001-01-01
Cepheids are the primary distance indicators for extragalactic astronomy and therefore are of very high astrophysical interest. Unfortunately, they are rare stars, situated very far from Earth.Though they are supergiants, their typical angular diameter is only a few milliarcseconds, making them very challenging targets even for long-baseline interferometers. We report observations that were obtained in the K prime band (2-2.3 microns), on the Cepheid Zeta Geminorum with the FLUOR beam combiner, installed at the IOTA interferometer. The mean uniform disk angular diameter was measured to be 1.64 +0.14 -0.16 mas. Pulsational variations are not detected at a significant statistical level, but future observations with longer baselines should allow a much better estimation of their amplitude. The distance to Zeta Gem is evaluated using Baade-Wesselink diameter determinations, giving a distance of 502 +/- 88 pc.
Measurement of polarization with the Degree Angular Scale Interferometer.
Leitch, E M; Kovac, J M; Pryke, C; Carlstrom, J E; Halverson, N W; Holzapfel, W L; Dragovan, M; Reddall, B; Sandberg, E S
Measurements of the cosmic microwave background (CMB) radiation can reveal with remarkable precision the conditions of the Universe when it was approximately 400,000 years old. The three most fundamental properties of the CMB are its frequency spectrum (which determines the temperature), and the fluctuations in both the temperature and polarization across a range of angular scales. The frequency spectrum has been well determined, and considerable progress has been made in measuring the power spectrum of the temperature fluctuations. But despite many efforts to measure the polarization, detection of this property of the CMB has hitherto been beyond the reach of even the most sensitive observations. Here we describe the Degree Angular Scale Interferometer (DASI), an array of radio telescopes, which for the past two years has conducted polarization-sensitive observations of the CMB from the Amundsen-Scott South Pole research station.
Analogies between optical and quantum mechanical angular momentum
Nienhuis, Gerard
2017-02-01
The insight that a beam of light can carry orbital angular momentum (AM) in its propagation direction came up in 1992 as a surprise. Nevertheless, the existence of momentum and AM of an electromagnetic field has been well known since the days of Maxwell. We compare the expressions for densities of AM in general three-dimensional modes and in paraxial modes. Despite their classical nature, these expressions have a suggestive quantum mechanical appearance, in terms of linear operators acting on mode functions. In addition, paraxial wave optics has several analogies with real quantum mechanics, both with the wave function of a free quantum particle and with a quantum harmonic oscillator. We discuss how these analogies can be applied. This article is part of the themed issue 'Optical orbital angular momentum'.
MRI-driven angular momentum transport in protoplanetary disks
Fromang, Sebastien
2013-01-01
Angular momentum transport in accretion disk has been the focus of intense research in theoretical astrophysics for many decades. In the past twenty years, MHD turbulence driven by the magnetorotational instability has emerged as an efficient mechanism to achieve that goal. Yet, many questions and uncertainties remain, among which the saturation level of the turbulence. The consequences of the magnetorotational instability for planet formation models are still being investigated. This lecture, given in September 2012 at the school "Role and mechanisms of angular momentum transport in the formation and early evolution of stars" in Aussois (France), aims at introducing the historical developments, current status and outstanding questions related to the magnetorotational instability that are currently at the forefront of academic research.
MRI-driven angular momentum transport in protoplanetary disks
Fromang, S.
2013-09-01
Angular momentum transport in accretion disk has been the focus of intense research in theoretical astrophysics for many decades. In the past twenty years, MHD turbulence driven by the magnetorotational instability has emerged as an efficient mechanism to achieve that goal. Yet, many questions and uncertainties remain, among which the saturation level of the turbulence. The consequences of the magnetorotational instability for planet formation models are still being investigated. This lecture, given in September 2012 at the school "Role and mechanisms of angular momentum transport in the formation and early evolution of stars" in Aussois (France), aims at introducing the historical developments, current status and outstanding questions related to the magnetorotational instability that are currently at the forefront of academic research.
Hybrid nonlinear model of the angular vestibulo-ocular reflex.
Ranjbaran, Mina; Galiana, Henrietta L
2013-01-01
A hybrid nonlinear bilateral model for the horizontal angular vestibulo-ocular reflex (AVOR) is presented in this paper. The model relies on known interconnections between saccadic burst circuits in the brainstem and ocular premotor areas in the vestibular nuclei during slow and fast phase intervals. A viable switching strategy for the timing of nystagmus events is proposed. Simulations show that this hybrid model replicates AVOR nystagmus patterns that are observed in experimentally recorded data.
Characterization of the Bell-Shaped Vibratory Angular Rate Gyro
Directory of Open Access Journals (Sweden)
Junfang Fan
2013-08-01
Full Text Available The bell-shaped vibratory angular rate gyro (abbreviated as BVG is a novel shell vibratory gyroscope, which is inspired by the Chinese traditional bell. It sensitizes angular velocity through the standing wave precession effect. The bell-shaped resonator is a core component of the BVG and looks like the millimeter-grade Chinese traditional bell, such as QianLong Bell and Yongle Bell. It is made of Ni43CrTi, which is a constant modulus alloy. The exciting element, control element and detection element are uniformly distributed and attached to the resonator, respectively. This work presents the design, analysis and experimentation on the BVG. It is most important to analyze the vibratory character of the bell-shaped resonator. The strain equation, internal force and the resonator's equilibrium differential equation are derived in the orthogonal curvilinear coordinate system. When the input angular velocity is existent on the sensitive axis, an analysis of the vibratory character is performed using the theory of thin shells. On this basis, the mode shape function and the simplified second order normal vibration mode dynamical equation are obtained. The coriolis coupling relationship about the primary mode and secondary mode is established. The methods of the signal processing and control loop are presented. Analyzing the impact resistance property of the bell-shaped resonator, which is compared with other shell resonators using the Finite Element Method, demonstrates that BVG has the advantage of a better impact resistance property. A reasonable means of installation and a prototypal gyro are designed. The gyroscopic effect of the BVG is characterized through experiments. Experimental results show that the BVG has not only the advantages of low cost, low power, long work life, high sensitivity, and so on, but, also, of a simple structure and a better impact resistance property for low and medium angular velocity measurements.
Angular distributions and total yield of laser ablated silver
DEFF Research Database (Denmark)
Svendsen, Winnie Edith; Nordskov, A.; Schou, Jørgen;
1997-01-01
The angular distribution of laser ablated silver has been measured in situ with a newly constructed setup with an array of microbalances. The distribution is strongly peaked in the forward direction corresponding to cospθ, where p varies between 5 and 9 for laser fluences from 2 to 7 J/cm2 at 355...... nm for a beam spot of 0.015 cm2. The total deposited yield is of the order 1015 Ag-atoms per pulse....
Angular correlation of annihilation photons in frozen aqueous solutions
DEFF Research Database (Denmark)
Milosevic-Kvajic, M.; Mogensen, O. E.; Kvajic, G.
1972-01-01
Linear‐slit angular correlation curves were obtained at about −140°C for frozen aqueous solutions of HF, HCl, HBr, HI, NH3, FeCl2, FeCl3, NaI, H2SO4, NHO3, MnSO4, KMnO4, K2Cr2O7, NaOH, and LiOH. We found no appreciable influence of a 4% concentration of the last seven impurities. Only halide‐cont...
Angular correlations in the double Drell-Yan process
Energy Technology Data Exchange (ETDEWEB)
Kasemets, Tomas; Diehl, Markus
2012-10-15
We study the impact of parton correlations on the double Drell-Yan process, i.e. on the production of two electroweak gauge bosons by double parton scattering in a single proton-proton collision. Spin correlations between two partons in a proton are shown to change the overall rate of the process and to induce characteristic angular correlations between the decay leptons of the two gauge bosons.
Shape evolution with angular momentum in Lu isotopes
Kardan, Azam; Sayyah, Sepideh
2016-06-01
The nuclear potential energies of Lu isotopes with neutron number N = 90 - 98 up to high spins are computed within the framework of the unpaired cranked Nilsson-Strutinsky method. The potential and the macroscopic Lublin-Strasbourg drop (LSD) energy-surface diagrams are analyzed in terms of quadrupole deformation and triaxiality parameter. The shape evolution of these isotopes with respect to angular momentum, as well as the neutron number is studied.
BaF2 TIME DIFFERENTIAL PERTURBED ANGULAR DISTRIBUTION SPECTROMETER
Institute of Scientific and Technical Information of China (English)
朱升云; 勾振辉; 等
1994-01-01
A BaF2 time differential perturbed angular distribution spectrometer has been established at the HI-13 tandem accelerator in CIAE.The time resolution of the spectrometer is 195ps and the nonlinearity is less than 2%.The spectrometer works very stably and no time drift is found over a period of experimental runs.This spectrometer has been successfully used in the g-factor measurement of 43Sc(19/2-,3.1232MeV).
Separability criteria with angular and Hilbert space averages
Fujikawa, Kazuo; Oh, C. H.; Umetsu, Koichiro; Yu, Sixia
2016-05-01
The practically useful criteria of separable states ρ =∑kwkρk in d = 2 × 2 are discussed. The equality G(a , b) = 4 [ - ] = 0 for any two projection operators P(a) and P(b) provides a necessary and sufficient separability criterion in the case of a separable pure state ρ = | ψ > Werner state is applied to two photon systems, it is shown that the Hilbert space average can judge its inseparability but not the geometrical angular average.
Angular characteristics of a multimode fiber surface plasmon resonance sensor
Tan, Zhixin; Li, Xuejin; Chen, Yuzhi; Hong, Xueming; Fan, Ping
2015-01-01
In this paper the angular characteristics of a multimode fiber SPR sensor are investigated theoretically. By separating the contributions of beams incident at different angles, a compact model is presented to predict the shift of the resonance wavelength with respect to the angle and the environmental refractive index. The result suggests that the performance of conventional fiber SPR sensors can be substantially improved by optimizing the incident angle.
Rueda de bicicleta en movimiento y momento angular
2013-01-01
Somos capaces de mantenernos erguidos mientras la bicicleta que montamos semueve, pero si ésta se detiene, nos inclinamos con ella y caemos. En este video observaremos este fenómeno utilizando una demostración experimental de física basada en una rueda de bicicleta. También analizaremos lo que sucede empleando magnitudes físicas como el momento angular de la rueda y los momentos de fuerza que actúan sobre ella.
Transport and influence of angular momentum in collapsing dense cores
Hennebelle, P.
2013-09-01
Angular momentum is playing a key role during the collapse of prestellar cores since it is leading to disk formation and to some extent to binary formation. On the other hand, it has long been recognized that the stars possess a tiny fraction of the initial momentum that their parent clouds retain, an issue known as the "angular momentum problem". In these lectures, we attempt to present the most recent calculations performed to investigate the angular momentum transport and the influence angular momentum has, during the collapse of prestellar cores. After a brief introduction of the star formation context and a broad description of the important features within collapsing cores, we discuss the so-called catastrophic braking. Indeed when magnetic field and rotation axis are aligned, the magnetic braking is so efficient that the formation of early disks is completely prevented. We then present the various studies which have attempted to explore the robustness of this efficient transport including influence of non-ideal MHD, misalignment between magnetic field and rotation axis and turbulence. While the role of the first, is not entirely clear; the two other effects diminish the efficacity of the magnetic braking making the issue less severe than in the pure ideal MHD aligned configuration. Finally, we discuss the fragmentation of low and high mass cores with particular emphasis on the impact of the magnetic field. In particular, we discuss the drastic stabilization that magnetic field has on low mass cores and the possible solution to this apparent conundrum. In the context of high mass stars, its influence is much more limited reducing the number of fragments by a factor of the order of two. However when both radiative feedback and magentic field are included, the fragmentation is very significantly reduced.
Angular dependence of spin-orbit spin-transfer torques
Lee, Ki-Seung
2015-04-06
In ferromagnet/heavy-metal bilayers, an in-plane current gives rise to spin-orbit spin-transfer torque, which is usually decomposed into fieldlike and dampinglike torques. For two-dimensional free-electron and tight-binding models with Rashba spin-orbit coupling, the fieldlike torque acquires nontrivial dependence on the magnetization direction when the Rashba spin-orbit coupling becomes comparable to the exchange interaction. This nontrivial angular dependence of the fieldlike torque is related to the Fermi surface distortion, determined by the ratio of the Rashba spin-orbit coupling to the exchange interaction. On the other hand, the dampinglike torque acquires nontrivial angular dependence when the Rashba spin-orbit coupling is comparable to or stronger than the exchange interaction. It is related to the combined effects of the Fermi surface distortion and the Fermi sea contribution. The angular dependence is consistent with experimental observations and can be important to understand magnetization dynamics induced by spin-orbit spin-transfer torques.
Angular Momentum in the Formation of Disk Galaxies
Institute of Scientific and Technical Information of China (English)
LUO Zhi-Jian; SHU Cheng-Gang
2004-01-01
@@ Within the current framework of disk galaxy formation, we discuss the resulted surface-density profiles according to the theoretical angular momentum distributions (AMDs) presented by Bullock et al. [Astrophys. J.555 (2001) 240(B01)] for the ACDM cosmology in both spherical and cylindric coordinates. It is found that the derived surface density distribution of a disk in the outer region is in general similar to an exponential disk for both the theoretical AMDs. In the central region, the results from both the theoretical AMDs are inconsistent with observations whatever the disk bar-instability is taken into account or not. The cylindric form of the theoretical AMD leads to the bar-instability more easily for a give galaxy than that for spherical AMD, which could result in a more massive bulge. After comparing the model predictions with our Milky Way galaxy, we find that the theoretical AMDs predict larger mass fractions of baryons with low angular momentum than the observed ones, which would lead to the disk sizes to be smaller. Two possible processes which could solve the angular momentum problem are discussed.
Optimisation of surface passivation for highly reliable angular AMR sensors
Energy Technology Data Exchange (ETDEWEB)
Isler, M.; Christoffer, B.; Schoer, G.; Philippsen, B.; Mahnke, M.; Thorns, A.; Riethmueller, W.; Matz, H.; Tobescu, C. [NXP Semiconductors, Stresemannallee 101, 22529 Hamburg (Germany); Vanhelmont, F.; Wolters, R. [NXP Semiconductors, High Tech Campus 4, 5656 AE Eindhoven (Netherlands); Engelen, R.; Opran, A. [Philips Applied Technologies, High Tech Campus 7, 5656 AE Eindhoven (Netherlands); Stolk, P. [NXP Semiconductors, Gerstweg 2, 6534 AE Nijmegen (Netherlands)
2010-02-15
For state-of-the-art angular sensors based on the anisotropic magnetoresistive (AMR) effect in NiFe layers, the angular accuracy over time is limited by a drift of the offset voltage of the Wheatstone bridge configuration. It is shown that the interaction of the passivation layer and the magnetic permalloy is crucial for the drift of the offset voltage. By investigating the time and temperature dependence, the offset drift is attributed to stress relief of the PECVD passivation layer due to microstructural changes. Hydrogen outdiffusion from the passivation layer is involved in the observed stress evolution. It is demonstrated that optimising the passivation layer composition as well as the time of the subsequent annealing is beneficial for stress stabilisation of the permalloy-passivation layer system. With this optimised passivation layer a significant offset drift reduction of the NiFe Wheatstone bridge has been achieved resulting in highly accurate and long-term stable angular AMR sensors. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Angular dependence of primordial trispectra and CMB spectral distortions
Shiraishi, Maresuke; Bartolo, Nicola; Liguori, Michele
2016-10-01
Under the presence of anisotropic sources in the inflationary era, the trispectrum of the primordial curvature perturbation has a very specific angular dependence between each wavevector that is distinguishable from the one encountered when only scalar fields are present, characterized by an angular dependence described by Legendre polynomials. We examine the imprints left by curvature trispectra on the TTμ bispectrum, generated by the correlation between temperature anisotropies (T) and chemical potential spectral distortions (μ) of the Cosmic Microwave Background (CMB). Due to the angular dependence of the primordial signal, the corresponding TTμ bispectrum strongly differs in shape from TTμ sourced by the usual gNL or τNL local trispectra, enabling us to obtain an unbiased estimation. From a Fisher matrix analysis, we find that, in a cosmic-variance-limited (CVL) survey of TTμ, a minimum detectable value of the quadrupolar Legendre coefficient is d2 ~ 0.01, which is 4 orders of magnitude better than the best value attainable from the TTTT CMB trispectrum. In the case of an anisotropic inflationary model with a f(phi)F2 interaction (coupling the inflaton field phi with a vector kinetic term F2), the size of the curvature trispectrum is related to that of quadrupolar power spectrum asymmetry, g*. In this case, a CVL measurement of TTμ makes it possible to measure g* down to 10‑3.
Low Angular Momentum in Clumpy, Turbulent Disk Galaxies
Obreschkow, Danail; Bassett, Robert; Fisher, David B; Abraham, Roberto G; Wisnioski, Emily; Green, Andrew W; McGregor, Peter J; Damjanov, Ivana; Popping, Attila; Jorgensen, Inger
2015-01-01
We measure the stellar specific angular momentum jstar=Jstar/Mstar in four nearby (redshift z~0.1) disk galaxies that have stellar masses Mstar near the break M* of the galaxy mass function, but look like typical star-forming disks at z~2 in terms of their low stability (Q~1), clumpiness, high ionized gas dispersion (40-50 km/s), high molecular gas fraction (20-30%) and rapid star formation (~20 Msun/yr). Combining high-resolution (Keck-OSIRIS) and large-radius (Gemini-GMOS) spectroscopic maps, only available at low z, we discover that these targets have ~3 times less stellar angular momentum than typical local spiral galaxies of equal stellar mass and bulge fraction. Theoretical considerations show that this deficiency in angular momentum is the main cause of their low stability, while the high gas fraction plays a complementary role. Interestingly, the low jstar values of our targets are similar to those expected in the M*-population at higher z from the approximate theoretical scaling jstar~(1+z)^(-1/2) at...
Wigner functions for the pair angle and orbital angular momentum
Kastrup, H. A.
2016-12-01
The problem of constructing physically and mathematically well-defined Wigner functions for the canonical pair angle θ and angular momentum p is solved. While a key element for the construction of Wigner functions for the planar phase space {(q ,p ) ∈R2} is the Heisenberg-Weyl group, the corresponding group for the cylindrical phase space {(θ ,p ) ∈S1×R } is the Euclidean group E (2 ) of the plane and its unitary representations. Here the angle θ is replaced by the pair (cosθ ,sinθ ) , which corresponds uniquely to the points on the unit circle. The main structural properties of the Wigner functions for the planar and the cylindrical phase spaces are strikingly similar. A crucial role is played by the s i n c function, which provides the interpolation for the discontinuous quantized angular momenta in terms of the continuous classical ones, in accordance with the famous Whittaker cardinal function well known from interpolation and sampling theories. The quantum mechanical marginal distributions for the angle (continuous) and angular momentum (discontinuous) are, as usual, uniquely obtained by appropriate integrations of the (θ ,p ) Wigner function. Among the examples discussed is an elementary system of simple cat states.
Quark Orbital Angular Momentum in the MIT Bag Model
Courtoy, A
2016-01-01
We present the results for the Generalized Transverse Momentum Distribution related to quark Orbital Angular Momentum, {\\it i.e.} $F_{14}$, in the MIT bag model. This model has been modified to include the Peierls--Yoccoz projection to restore translational invariance. Such a modification allows to fulfill more satisfactorily basic sum rules, that would otherwise be less elegantly carried out with the original version. Using the same model, we have calculated the twist-$3$ GPD that corresponds to Orbital Angular Momentum \\`a la Ji, through the Penttinen--Polyakov--Shuvaev--Strikman sum rule. Recently, a new relation between the two definitions of the quark Orbital Angular Momentum at the density level has been proposed, which we illustrate here within the model. The sum rule is fulfilled. Still within the framework of the MIT bag model, we analyze the Wandzura--Wilczek expression for the GPD of interest. The genuine quark-gluon contribution is evaluated directly thanks to the equation of motion of the bag, wh...
Statistical mechanics of collisionless orbits. IV. Distribution of angular momentum
Williams, Liliya L R; Wojtak, Radoslaw
2014-01-01
It has been shown in previous work that DARKexp, which is a theoretically derived, maximum entropy, one shape parameter model for isotropic collisionless systems, provides very good fits to simulated and observed dark-matter halos. Specifically, it fits the energy distribution, N(E), and the density profiles, including the central cusp. Here, we extend DARKexp N(E) to include the distribution in angular momentum, L^2, for spherically symmetric systems. First, we argue, based on theoretical, semi-analytical, and simulation results, that while dark-matter halos are relaxed in energy, they are not nearly as relaxed in angular momentum, which precludes using maximum entropy to uniquely derive N(E,L^2). Instead, we require that when integrating N(E,L^2) over squared angular momenta one retrieves the DARKexp N(E). Starting with a general expression for N(E,L^2) we show how the distribution of particles in L^2 is related to the shape of the velocity distribution function, VDF, and velocity anisotropy profile, \\beta(...
A universal angular momentum profile for dark matter haloes
Liao, Shihong; Chu, M -C
2016-01-01
The angular momentum distribution in dark matter haloes and galaxies is a key ingredient in understanding their formation. Especially, the internal distribution of angular momenta is closely related to the formation of disk galaxies. In this article, we use haloes identified from a high-resolution simulation, the Bolshoi simulation, to study the spatial distribution of specific angular momenta, $j(r,\\theta)$. We show that by stacking haloes with similar masses to increase the signal-to-noise ratio, the profile can be fitted as a simple function, $j(r,\\theta)=j_s \\sin^2(\\theta/\\theta_s) (r/r_s)^2/(1+r/r_s)^4 $, with three free parameters, $j_s, r_s$, and $\\theta_s$. Specifically, $j_s$ correlates with the halo mass $M_\\mathrm{vir}$ as $j_s\\propto M_\\mathrm{vir}^{2/3}$, $r_s$ has a weak dependence on the halo mass as $r_s \\propto M_\\mathrm{vir}^{0.040}$, and $\\theta_s$ is independent of $M_\\mathrm{vir}$. This profile agrees with that from a rigid shell model, though its origin is unclear. Our universal specific...
Angular Momentum Constraints on GMC formation in M33
Rosolowsky, E.; Engargiola, G.; Plambeck, R.; Blitz, L.
2001-12-01
We present the results of the complete CO 12CO(1-> 0) survey of the molecular gas in M33. These observations represent the first survey of all of the GMCs in a spiral galaxy; CO surveys of the Milky Way are too severely blended in some regions to separate the GMCs from one another. These observations show that individual molecular clouds share many properties with those found in the Milky Way although the most massive GMC in M33 has a mass of only 7x 105 Msun and is not associated with an Hii region. Moreover, the specific angular momentum of the GMCs is more than an order of magnitude smaller than expected for basic formation scenarios. The observational campaign consists of two parts: 1) a complete survey of the star forming disk which represents a complete census of GMCs down to the Taurus cloud mass at low spatial resolution and high surface brightness sensitivity and 2) high resolution follow-up observations which spatially resolve the molecular clouds providing information on rotation properties, virial masses, and morphology. From the latter, we estimate the angular momentum imparted through galactic shear by Jeans collapse, the Toomre instability and the Parker instability, all of which impart much more angular momentum to the clouds than is observed. We propose the magnetic fields that thread the molecular clouds and connect to the diffuse interstellar medium brake the spin-up of the progenitor gas, suggesting that the formation of GMCs is a magnetohydrodynamic process.
Angular Fock coefficients. Fixing the errors, and further development
Liverts, Evgeny Z
2015-01-01
The angular coefficients $\\psi_{k,p}(\\alpha,\\theta)$ of the Fock expansion characterizing the S-state wave function of the two-electron atomic system, are calculated in hyperspherical angular coordinates $\\alpha$ and $\\theta$. To solve the problem the Fock recurrence relations separated into the independent individual equations associated with definite power $j$ of the nucleus charge $Z$, are applied. The "pure" $j$-components of the angular Fock coefficients, orthogonal to of the hyperspherical harmonics $Y_{kl}$, are found for even values of $k$. To this end, the specific coupling equation is proposed and applied. Effective techniques for solving the individual equations with simplest nonseparable and separable right-hand sides are proposed. Some mistakes/misprints made earlier in representations of $\\psi_{2,0}$, were noted and corrected. All $j$-components of $\\psi_{4,1}$ and the majority of components and subcomponents of $\\psi_{3,0}$ are calculated and presented for the first time. All calculations were ...
Revisiting the WMAP - NVSS angular cross correlation. A skeptic view
Hernandez-Monteagudo, Carlos
2009-01-01
In the context of the study of the ISW, we revisit the angular cross correlation of WMAP CMB data with the NVSS radio survey. We compute 2-point cross functions between the two surveys in real and in Fourier space, paying particular attention on the dependence of results on the flux of NVSS radio sources, the angular scales where correlations arise and the comparison with theoretical expectations. We reproduce previous results that claim an excess of correlation in the angular correlation function (ACF), and we also find some (low significance) similarity between the CMB and radio galaxy data in the multipole range $\\el \\in $ [10, 25]. However, the S/N in the ACFs increases with higher flux thresholds for NVSS sources, but drops a $\\sim$ 30 - 50% in separations of the order of a pixel size, suggesting some residual point source contribution. When restricting our analyses to multipoles $\\el \\gt $60, we fail to find any evidence for cross correlation in the range $\\el \\in [2,10]$, where according to the model p...
Time-delay Cosmography: Increased Leverage with Angular Diameter Distances
Jee, Inh; Suyu, Sherry H; Huterer, Dragan
2015-01-01
Strong lensing time-delay systems constrain cosmological parameters via the so-called time-delay distance and the angular diameter distance to the lens. In previous studies, only the former information was used. In this paper, we show that the cosmological constraints improve significantly when the latter information is also included. Specifically, the angular diameter distance plays a crucial role in breaking the degeneracy between the curvature of the Universe and the time-varying equation of state of dark energy. Using a mock sample of 55 bright quadruple lens systems based on expectations for ongoing/future imaging surveys, we find that adding the angular diameter distance information to the time-delay distance information and the cosmic microwave background data of Planck improves the constraint on the constant equation of state by 30%, on the time variation in the equation of state by a factor of two, and on the Hubble constant in the flat $\\Lambda$CDM model by a factor of two. Therefore, previous forec...
Unsafe but Calculable: Ratios of Angularities in Perturbative QCD
Larkoski, Andrew J
2013-01-01
Infrared- and collinear-safe (IRC-safe) observables have finite cross sections to each fixed-order in perturbative QCD. Generically, ratios of IRC-safe observables are themselves not IRC safe and do not have a valid fixed-order expansion. Nevertheless, in this paper we present an explicit method to calculate the cross section for a ratio observable in perturbative QCD with the help of resummation. We take the IRC-safe jet angularities as an example and consider the ratio formed from two angularities with different angular exponents. While the ratio observable is not IRC safe, it is "Sudakov safe", meaning that the perturbative Sudakov factor exponentially suppresses the singular region of phase space. At leading logarithmic (LL) order, the distribution is finite but has a peculiar expansion in the square root of the strong coupling constant, a consequence of IRC unsafety. The accuracy of the LL distribution can be further improved with higher-order resummation and fixed-order matching. Non-perturbative effect...
Reconstructing the galaxy redshift distribution from angular cross power spectra
Sun, L; Tao, C
2015-01-01
The control of photometric redshift (photo-$z$) errors is a crucial and challenging task for precision weak lensing cosmology. The spacial cross-correlations (equivalently, the angular cross power spectra) of galaxies between tomographic photo-$z$ bins are sensitive to the true redshift distribution $n_i(z)$ of each bin and hence can help calibrate the photo-$z$ error distribution for weak lensing surveys. Using Fisher matrix analysis, we investigate the contributions of various components of the angular power spectra to the constraints of $n_i(z)$ parameters and demonstrate the importance of the cross power spectra therein, especially when catastrophic photo-$z$ errors are present. We further study the feasibility of reconstructing $n_i(z)$ from galaxy angular power spectra using Markov Chain Monte Carlo estimation. Considering an LSST-like survey with $10$ photo-$z$ bins, we find that the underlying redshift distribution can be determined with a fractional precision ($\\sigma(\\theta)/\\theta$ for parameter $\\...
Time-delay cosmography: increased leverage with angular diameter distances
Jee, I.; Komatsu, E.; Suyu, S. H.; Huterer, D.
2016-04-01
Strong lensing time-delay systems constrain cosmological parameters via the so-called time-delay distance and the angular diameter distance to the lens. In previous studies, only the former information was used in forecasting cosmographic constraints. In this paper, we show that the cosmological constraints improve significantly when the latter information is also included. Specifically, the angular diameter distance plays a crucial role in breaking the degeneracy between the curvature of the Universe and the time-varying equation of state of dark energy. Using a mock sample of 55 bright quadruple lens systems based on expectations for ongoing/future imaging surveys, we find that adding the angular diameter distance information to the time-delay distance information and the Planck's measurements of the cosmic microwave background anisotropies improves the constraint on the constant equation of state by 30%, on the time variation in the equation of state by a factor of two, and on the Hubble constant in the flat ΛCDM model by a factor of two. Therefore, previous forecasts for the statistical power of time-delay systems were overly pessimistic, i.e., time-delay systems are more powerful than previously appreciated.
Energy and angular momentum deposition during Common envelope evolution
Directory of Open Access Journals (Sweden)
Noam Soker
2004-01-01
Full Text Available Tomo en consideraci on tres procesos que incrementan la tasa de p erdida de masa de la envolvente com un de una gigante de la secuencia principal o de una compa~nera enana blanca que se precipita en espiral dentro de su envolvente. Considero el dep osito de energ a orbital y momento angular orbital en la envolvente de la gigante y la formaci on de \\jets" por la compa~nera acreciente que se propagan dentro de la envolvente. Encuentro que en muchos casos el dep osito del momento angular en la envolvente puede ser m as importante para el proceso de p erdida de masa que el dep osito de energ a orbital. En etapas tempranas de la evoluci on com un de la envolvente los "jets" que son expulsados por una compa~nera acreciente, en particular una enana blanca que orbita dentro de las regiones exteriores de la envolvente de la gigante, tambi en pueden dominar sobre el dep osito de energ a. Esto implica que los estudios que ignoran el dep osito del momento angular dentro de la envolvente y los efectos de la compa~nera acreciente pueden llegar a conclusiones err oneas.
Stiffness and Angular Deflection analysis of Revolute Manipulator
Directory of Open Access Journals (Sweden)
Pundru Srinivasa Rao
2014-03-01
Full Text Available This paper proposed to determine the Cartesian stiffness matrix and angular deflection analysis of revolute manipulator. The selected manipulator has rigid fixed link, two movable links and two rotary joints with joint stiffness coefficients are taken into account. The kinematic model of revolute joint manipulator has considered as a planar kinematic chain, which is composed by rigid fixed link and two revolute joints with clearance and deformable elements. The calculation of stiffness matrix depends on Jacobian matrix and change of configuration. The rotational joints are modeled as torsion springs with the same stiffness constant. The relative angular deflections are proportional to the actuated torques taken into account. The subject of this paper has to describe a method for stiffness analysis of serial manipulator. In the present work is to derive the stiffness matrix and angular deflection equations in the Robotic manipulator under the consideration of two-link optimum geometry model for rotary joint manipulator. The stiffness values are measured by displacements of its revolute links loaded by force.
How we are building a complex Angular 2 application at Inspire
CERN. Geneva
2017-01-01
In this talk, at first we will talk about some basic and advanced Angular 2 concepts, then we will share our experiences with Angular 2 that we had so far while building a complex library and web applications at Inspire.
Institute of Scientific and Technical Information of China (English)
ZHANG Yi-Xin; CANG Ji
2009-01-01
Effects of atmospheric turbulence tilt, defocus, astigmatism and coma aberrations on the orbital angular mo-mentum measurement probability of photons propagating in weak turbulent regime are modeled with Rytov approximation. By considering the resulting wave as a superposition of angular momentum eigenstates, the or-bital angular momentum measurement probabilities of the transmitted digit axe presented. Our results show that the effect of turbulent tilt aberration on the orbital angular momentum measurement probabilities of photons is the maximum among these four kinds of aberrations. As the aberration order increases, the effects of turbulence aberrations on the measurement probabilities of orbital angular momentum generally decrease, whereas the effect of turbulence defoens can be ignored. For tilt aberration, as the difference between the measured orbital angular momentum and the original orbital angular momentum increases, the orbital angular momentum measurement probabifity decreases.
Vestibular adaptation to space in monkeys
Dai, M.; Raphan, T.; Kozlovskaya, I.; Cohen, B.
1998-01-01
Otolith-induced eye movements of rhesus monkeys were studied before and after the 1989 COSMOS 2044 and the 1992 to 1993 COSMOS 2229 flights. Two animals flew in each mission for approximately 2 weeks. After flight, spatial orientation of the angular vestibulo-ocular reflex was altered. In one animal the time constant of postrotatory nystagmus, which had been shortened by head tilts with regard to gravity before flight, was unaffected by the same head tilts after flight. In another animal, eye velocity, which tended to align with a gravitational axis before flight, moved toward a body axis after flight. This shift of orientation disappeared by 7 days after landing. After flight, the magnitude of compensatory ocular counter-rolling was reduced by about 70% in both dynamic and static tilts. Modulation in vergence in response to naso-occipital linear acceleration during off-vertical axis rotation was reduced by more than 50%. These changes persisted for 11 days after recovery. An up and down asymmetry of vertical nystagmus was diminished for 7 days. Gains of the semicircular canal-induced horizontal and vertical angular vestibulo-ocular reflexes were unaffected in both flights, but the gain of the roll angular vestibulo-ocular reflex was decreased. These data indicate that there are short- and long-term changes in otolith-induced eye movements after adaptation to microgravity. These experiments also demonstrate the unique value of the monkey as a model for studying effects of vestibular adaptation in space. Eye movements can be measured in three dimensions in response to controlled vestibular and visual stimulation, and the results are directly applicable to human beings. Studies in monkeys to determine how otolith afferent input and central processing is altered by adaptation to microgravity should be an essential component of future space-related research.
DEFF Research Database (Denmark)
Rist, Lucy; Campbell, Bruce Morgan; Frost, Peter
2013-01-01
in scientific articles, policy documents and management plans, but both understanding and application of the concept is mixed. This paper reviews recent literature from conservation and natural resource management journals to assess diversity in how the term is used, highlight ambiguities and consider how...... the concept might be further assessed. AM is currently being used to describe many different management contexts, scales and locations. Few authors define the term explicitly or describe how it offers a means to improve management outcomes in their specific management context. Many do not adhere to the idea......Adaptive management (AM) emerged in the literature in the mid-1970s in response both to a realization of the extent of uncertainty involved in management, and a frustration with attempts to use modelling to integrate knowledge and make predictions. The term has since become increasingly widely used...
Hancox, Cindy I; Doret, S Charles; Hummon, Matthew T; Krems, Roman V; Doyle, John M
2005-01-14
The Zeeman relaxation rate in cold collisions of Ti(3d(2)4s(2) 3F2) with He is measured. We find that collisional transfer of angular momentum is dramatically suppressed due to the presence of the filled 4s(2) shell. The degree of electronic interaction anisotropy, which is responsible for Zeeman relaxation, is estimated to be about 200 times smaller in the Ti-He complex than in He complexes with typical non-S-state atoms.
Berkhout, Gregorius C G; Beijersbergen, Marco W
2008-09-05
We present an efficient method for probing the orbital angular momentum of optical vortices of arbitrary sizes. This method, based on a multipoint interferometer, has its most important application in measuring the orbital angular momentum of light from astronomical sources, opening the way to interesting new astrophysics. We demonstrate its viability by measuring the orbital angular momentum of Laguerre-Gaussian laser beams.
New procedure for gear fault detection and diagnosis using instantaneous angular speed
Li, Bing; Zhang, Xining; Wu, Jili
2017-02-01
Besides the extreme complexity of gear dynamics, the fault diagnosis results in terms of vibration signal are sometimes easily misled and even distorted by the interference of transmission channel or other components like bearings, bars. Recently, the research field of Instantaneous Angular Speed (IAS) has attracted significant attentions due to its own advantages over conventional vibration analysis. On the basis of IAS signal's advantages, this paper presents a new feature extraction method by combining the Empirical Mode Decomposition (EMD) and Autocorrelation Local Cepstrum (ALC) for fault diagnosis of sophisticated multistage gearbox. Firstly, as a pre-processing step, signal reconstruction is employed to address the oversampled issue caused by the high resolution of the angular sensor and the test speed. Then the adaptive EMD is used to acquire a number of Intrinsic Mode Functions (IMFs). Nevertheless, not all the IMFs are needed for the further analysis since different IMFs have different sensitivities to fault. Hence, the cosine similarity metric is introduced to select the most sensitive IMF. Even though, the sensitive IMF is still insufficient for the gear fault diagnosis due to the weakness of the fault component related to the gear fault. Therefore, as the final step, ALC is used for the purpose of signal de-noising and feature extraction. The effectiveness and robustness of the new approach has been validated experimentally on the basis of two gear test rigs with gears under different working conditions. Diagnosis results show that the new approach is capable of effectively handling the gear fault diagnosis i.e., the highlighted quefrency and its rahmonics corresponding to the rotary period and its multiple are displayed clearly in the cepstrum record of the proposed method.
Directory of Open Access Journals (Sweden)
D. Ashok Kumar
2016-02-01
Full Text Available Apparently weed is a major menace in crop production as it competes with crop for nutrients, moisture, space and light which resulting in poor growth and development of the crop and finally yield. Yield loss accounts for even more than 70% when crops are frown under unweeded condition with severe weed infestation. Weed management is the most significant process in the agricultural applications to improve the crop productivity rate and reduce the herbicide application cost. Existing weed detection techniques does not yield better performance due to the complex background, illumination variation and crop and weed overlapping in the agricultural field image. Hence, there arises a need for the development of effective weed identification technique. To overcome this drawback, this paper proposes a novel Wrapping Curvelet Transformation Based Angular Texture Pattern Extraction Method (WCTATP for weed identification. In our proposed work, Global Histogram Equalization (GHE is used improve the quality of the image and Adaptive Median Filter (AMF is used for filtering the impulse noise from the image. Plant image identification is performed using green pixel extraction and k-means clustering. Wrapping Curvelet transform is applied to the plant image. Feature extraction is performed to extract the angular texture pattern of the plant image. Particle Swarm Optimization (PSO based Differential Evolution Feature Selection (DEFS approach is applied to select the optimal features. Then, the selected features are learned and passed through an RVM based classifier to find out the weed. Edge detection and contouring is performed to identify the weed in the plant image. The Fuzzy rule-based approach is applied to detect the low, medium and high levels of the weed patchiness. From the experimental results, it is clearly observed that the accuracy of the proposed approach is higher than the existing Support Vector Machine (SVM based approaches. The proposed approach
A novel adaptive sliding mode control with application to MEMS gyroscope.
Fei, Juntao; Batur, Celal
2009-01-01
This paper presents a new adaptive sliding mode controller for MEMS gyroscope; an adaptive tracking controller with a proportional and integral sliding surface is proposed. The adaptive sliding mode control algorithm can estimate the angular velocity and the damping and stiffness coefficients in real time. A proportional and integral sliding surface, instead of a conventional sliding surface is adopted. An adaptive sliding mode controller that incorporates both matched and unmatched uncertainties and disturbances is derived and the stability of the closed-loop system is established. The numerical simulation is presented to verify the effectiveness of the proposed control scheme. It is shown that the proposed adaptive sliding mode control scheme offers several advantages such as the consistent estimation of gyroscope parameters including angular velocity and large robustness to parameter variations and external disturbances.
Dependence of the roll angular vestibuloocular reflex (aVOR) on gravity.
Yakushin, Sergei B; Xiang, Yongqing; Cohen, Bernard; Raphan, Theodore
2009-11-01
Little is known about the dependence of the roll angular vestibuloocular reflex (aVOR) on gravity or its gravity-dependent adaptive properties. To study gravity-dependent characteristics of the roll aVOR, monkeys were oscillated about a naso-occipital axis in darkness while upright or tilted. Roll aVOR gains were largest in the upright position and decreased by 7-15% as animals were tilted from the upright. Thus the unadapted roll aVOR gain has substantial gravitational dependence. Roll gains were also decreased or increased by 0.25 Hz, in- or out-of-phase rotation of the head and the visual surround while animals were prone, supine, upright, or in side-down positions. Gain changes, determined as a function of head tilt, were fit with a sinusoid; the amplitudes represented the amount of the gravity-dependent gain change, and the bias, the gravity-independent gain change. Gravity-dependent gain changes were absent or substantially smaller in roll (approximately 5%) than in yaw (25%) or pitch (17%), whereas gravity-independent gain changes were similar for roll, pitch, and yaw (approximately 20%). Thus the high-frequency roll aVOR gain has an inherent dependence on head orientation re gravity in the unadapted state, which is different from the yaw/pitch aVORs. This inherent gravitational dependence may explain why the adaptive circuits are not active when the head is tilted re gravity during roll aVOR adaptation. These behavioral differences support the idea that there is a fundamental difference in the central organization of canal-otolith convergence of the roll and yaw/pitch aVORs.
Directory of Open Access Journals (Sweden)
Jingrui Zhang
2014-02-01
Full Text Available An adaptive terminal sliding mode control for six-degree-of-freedom electromagnetic spacecraft formation flying (EMFF in near-Earth orbits is presented. By using terminal sliding mode (TSM technique, the output tracking error can converge to zero in finite time, and strong robustness with respect to disturbance forces can be guaranteed. Based on a rotated frame Fr and the adaptive TSM controller, the special magnetic moment of the steerable magnetic dipole is computed. The angular momentum management strategy (AMM is implemented in a periodically switching fashion, by which the angular momentum buildup was limited. Illustrative simulations of EMFF are conducted to verify the effectiveness of the proposed controller.
Orbital angular momentum of the laser beam and the second order intensity moments
Institute of Scientific and Technical Information of China (English)
高春清[1; 魏光辉[2; HorstWeber[3
2000-01-01
From the wave equation of a generalized beam the orbital angular momentum is studied. It is shown that the orbital angular momentum exists not only in the Laguerre-Gaussian beam, but in any beam with an angular-dependent structure. By calculating the second order intensity moments of the beam the relation between the orbital angular momentum and the second order moments 〈xθy〉, 〈yθx〉 is given. As an example the orbital angular momentum of the general astigmatic Gaussian beam is studied.
Orbital angular momentum of the laser beam and the second order intensity moments
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
From the wave equation of a generalized beam the orbital angular momentum is studied. It is shown that the orbital angular momentum exists not only in the Laguerre_Gaussian beam,but in any beam with an angular_dependent structure. By calculating the second order intensity moments of the beam the relation between the orbital angular momentum and the second order moments 〈xθy〉, 〈yθx〉 is given. As an example the orbital angular momentum of the general astigmatic Gaussian beam is studied.
Unidentified angular recurrent ulceration responsive to antiviral therapy
Directory of Open Access Journals (Sweden)
Rahmi Amtha
2013-03-01
Full Text Available Background: Recurrent ulcer on angular area is usually called stomatitis angularis. It is caused by many factors such as vertical dimension reduce, vitamin B12, and immune system deficiency, C. albicans and staphylococcus involvement. Clinically is characterized by painful fissure with erythematous base without fever. Purpose: to describe an unidentified angular ulcer proceeded by recurrent ulcers with no response of topical therapy. Case: An 18-years old male came to Oral Medicine clinic in RSCM who complained of angular recurrent ulcers since 3 years ago which developed on skin and bleed easily on mouth opening. Patient had fever before the onset of ulcers. Large, painful, irregular ulcers covered by red crustae on angular area bilaterally. Patient has been treated with various drugs without improvement and lead to mouth opening limitation. Intra oral shows herpetiformtype of ulcer and swollen of gingival. Case management: Provisional diagnosis was established as viral infection thus acyclovir 200 mg five times daily for two weeks and topical anti inflammation gel were administered. Blood test for IgG/IgM of HSV1 and HSV2 were non reactive, however ulceration showed a remarkable improvement. The ulcers healed completely after next 2 weeks with acyclovir. Conclusion: The angular ulceration on above patient failed to fulfill the criteria of stomatitis angularis or herpes labialis lesion. However it showed a good response to antiviral. Therefore, unidentified angular ulceration was appointed, as the lesion might be triggered by other type of human herpes virus or types of virus that response to acyclovir.Latar belakang: ulser rekuren pada sudut mulut biasanya disebut stomatitis angularis. Kelainan ini disebabkan oleh banyak faktor seperti berkurangnya dimensi vertikal, defisiensi vitamin B12 dan sistem kekebalan tubuh, infeksi C. albicans serta staphylococcus. Secara klinis kelainan ini ditandai dengan fisur sakit pada sudut mulut dengan dasar
Spin O decay angular distribution for interfering mesons in electroproduction
Energy Technology Data Exchange (ETDEWEB)
Funsten, H.; Gilfoyle, G.
1994-04-01
Self analyzing meson electroproduction experiments are currently being planned for the CEBAF CLAS detector. These experiments deduce the spin polarization of outgoing unstable spin s (?)0 mesons from their decay angular distribution, W({theta},{psi}). The large angular acceptance of the CLAS detector permits kinematic tracking of a sufficient number of these events to accurately determine electroproduction amplitudes from the deduced polarization. Maximum polarization information is obtained from W({theta},{psi}) for decay into spin 0 daughters. The helicity of the decaying meson is transferred to the daughter`s relative orbital angular momentum m-projection; none is {open_quotes}absorbed{close_quotes} into daughter helicities. The decaying meson`s helicity maximally appears in W({theta},{psi}). W({theta},{psi}) for spin 0 daughters has been derived for (1) vector meson electroproduction and (2) general interfering mesons produced by incident pions. This paper derives W({theta},{psi}) for electroproduction of two interfering mesons that decay into spin 0 daughters. An application is made to the case of interfering scalar and vector mesons. The derivation is an extension of work by Schil using the general decay formalism of Martin. The expressions can be easily extended to the case of N interfering mesons since interference occurs pairwise in the observable W ({theta},{psi}), a quadratic function of the meson amplitudes. The derivation uses the virtual photon density matrix of Schil which is transformed by a meson electroproduction transition operator, T. The resulting density matrix for the interfering mesons is then converted into a corresponding statistical tensor and contracted into the efficiency tensor for spin 0 daughters.
Angular momenta, dynamical masses, and mergers of brightest cluster galaxies
Energy Technology Data Exchange (ETDEWEB)
Jimmy; Tran, Kim-Vy [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Brough, Sarah [Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia); Gebhardt, Karl [Department of Astronomy, University of Texas at Austin, 1 University Station C1400, Austin, TX 78712 (United States); Von der Linden, Anja [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305-4085 (United States); Couch, Warrick J. [Centre for Astrophysics and Supercomputing, Swinburne University, P.O. Box 218, Hawthorn, VIC 3122 (Australia); Sharp, Rob [Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia)
2013-12-01
Using the VIMOS integral field unit (IFU) spectrograph on the Very Large Telescope, we have spatially mapped the kinematic properties of 10 nearby brightest cluster galaxies (BCGs) and 4 BCG companion galaxies located within a redshift of z = 0.1. In the hierarchical formation model, these massive galaxies (10{sup 10.5} M {sub ☉} < M {sub dyn} < 10{sup 11.9} M {sub ☉}) are expected to undergo more mergers than lower mass galaxies, and simulations show that dry minor mergers can remove angular momentum. We test whether BCGs have low angular momenta by using the λ {sub Re} parameter developed by the SAURON and ATLAS{sup 3D} teams and combine our kinematics with Sloan Digital Sky Survey photometry to analyze the BCGs' merger status. We find that 30% (3/10) of the BCGs and 100% of the companion galaxies (4/4) are fast rotators as defined by the ATLAS{sup 3D} criteria. Our fastest rotating BCG has a λ {sub Re} = 0.35 ± 0.05. We increase the number of BCGs analyzed from 1 in the combined SAURON and ATLAS{sup 3D} surveys to 11 BCGs total and find that above M {sub dyn} ∼ 11.5 M {sub ☉}, virtually all galaxies, regardless of environment, are slow rotators. To search for signs of recent merging, we analyze the photometry of each system and use the G – M {sub 20} selection criteria to identify mergers. We find that 40% ± 20% of our BCGs are currently undergoing or have recently undergone a merger (within 0.2 Gyr). Surprisingly, we find no correlation between galaxies with high angular momentum and morphological signatures of merging.
The vorticity and angular momentum budgets of Asian summer monsoon
Indian Academy of Sciences (India)
P L S Rao; U C Mohanty; P V S Raju; M A Arain
2004-09-01
The study delineates the vorticity and angular momentum balances of Asian summer monsoon during the evolution and established phases. It also elucidates the differences between these balances in the National Centre for Environmental Prediction/National Centre for Atmospheric Research (NCEP/NCAR) reanalysis and the National Centre for Medium Range Weather Forecasts (NCM- RWF) analysis fields. The NCEP/NCAR reanalysis for a 40 year period (1958-97) and the NCM- RWF analysis for a three year (1994-96) period are made use of for the purpose. The time mean summer monsoon circulation is bifurcated into stable mean and transient eddy components and the mean component is elucidated. The generation of vorticity due to stretching of isobars balances most of the vorticity transported out of the monsoon domain during the evolution period. However, during the established period, the transportation by the relative and planetary vorticity components exceeds the generation due to stretching. The effective balancing mechanism is provided by vorticity generation due to sub-grid scale processes. The flux convergence of omega and relative momenta over the monsoon domain is effectively balanced by pressure torque during the evolution and established phases. Nevertheless, the balance is stronger during the established period due to the increase in the strength of circulation. Both the NCMRWF and NCEP fields indicate the mean features related to vorticity and angular momentum budgets realistically. Apart from the oceanic bias (strong circulation over oceans rather than continents), the summer monsoon circulation indicated by the NCEP is feeble compared to NCMRWF. The significant terms in the large-scale budgets of vorticity and angular momentum enunciate this aspect.
On the transformations generated by the electromagnetic spin and orbital angular momentum operators
Fernandez-Corbaton, Ivan; Molina-Terriza, Gabriel
2013-01-01
We present a study of the properties of the transversal "spin angular momentum" and "orbital angular momentum" operators. We show that the "spin angular momentum" operators are generators of spatial translations which depend on helicity and frequency and that the "orbital angular momentum" operators generate transformations which are a sequence of this kind of translations and rotations. We give some examples of the use of these operators in light matter interaction problems. Their relationship with the helicity operator allows to involve the electromagnetic duality symmetry in the analysis. We also find that simultaneous eigenstates of the three "spin" operators and parity define a kind of standing modes which have been recently singled out for the interaction of light with chiral molecules. With respect to the relationship between "spin angular momentum", polarization, and total angular momentum, we show that, except for the case of a single plane wave, the total angular momentum of a beam is decoupled from...
Yuan, T -T; Rich, J
2013-01-01
With the rapid progress in metallicity gradient studies at high-redshift, it is imperative that we thoroughly understand the systematics in these measurements. This work investigates how the [NII]/Halpha ratio based metallicity gradients change with angular resolution, signal-to-noise (S/N), and annular binning parameters. Two approaches are used: 1. We downgrade the high angular resolution integral-field data of a gravitationally lensed galaxy and re-derive the metallicity gradients at different angular resolution; 2. We simulate high-redshift integral field spectroscopy (IFS) observations under different angular resolution and S/N conditions using a local galaxy with a known gradient. We find that the measured metallicity gradient changes systematically with angular resolution and annular binning. Seeing-limited observations produce significantly flatter gradients than higher angular resolution observations. There is a critical angular resolution limit beyond which the measured metallicity gradient is subst...
A Stern-Gerlach-like approach to electron orbital angular momentum measurement
Harvey, Tyler R
2016-01-01
Many methods now exist to prepare free electrons into orbital angular momentum states, and the predicted applications of these electron states as probes of materials and scattering processes are numerous. The development of electron orbital angular momentum measurement techniques has lagged behind. We show that coupling between electron orbital angular momentum and a spatially varying magnetic field produces an angular momentum-dependent focusing effect. We propose a design for an orbital angular momentum measurement device built on this principle. As the method of measurement is non-interferometric, the device works equally well for mixed, superposed and pure final orbital angular momentum states. The energy and orbital angular momentum distributions of inelastically scattered electrons may be simultaneously measurable with this technique.
Photon Angular Distribution and Polarization of Radiative Recombination
Institute of Scientific and Technical Information of China (English)
OU Wei-Ying; SHEN Tian-Ming; CHEN Chong-Yang; Roger Hutton; ZOU Ya-Ming
2005-01-01
@@ A systematic study is carried out on the angular distribution and polarization of photons emitted following radiative-recombination of bare and He-like ions of Ne, Ar, Ni and Mo with a unidirectional electron beam. In order to incorporate the screening effect due to inner-shell electrons, a distorted wave method is used. Scaling rules for polarization of the photon following radiative recombination to both bare and He-like ions are given for the incident energy regions up to six times the ionization threshold energy of the final state.
Manipulating atomic states via optical orbital angular-momentum
Institute of Scientific and Technical Information of China (English)
2008-01-01
Optical orbital angular-momentum(OAM)has more complex mechanics than the spin degree of photons,and may have a broad range of application.Manipulating atomic states via OAM has become an interesting topic.In this paper,we first review the general theory of generating adiabatic gauge field in ultracold atomic systems by coupling atoms to external optical fields with OAM,and point out the applications of the generated adiabatic gauge field.Then,we review our work in this field,including the generation of macroscopic superposition of vortex-antivortex states and spin Hall effect(SHE)in cold atoms.
Controlled angular redirection of light via nanoimprinted disordered gratings
DEFF Research Database (Denmark)
Buss, Thomas; Teisseire, Jérémie; Mazoyer, Simon
2013-01-01
Enhanced control of diffraction through transparent substrates is achieved via disordered gratings in a silica sol–gel film. Tailoring the degree of disorder allows tuning of the diffractive behavior from discrete orders into broad distributions over large angular range. Gratings of optical quality...... are formed by silica sol–gel nanoimprint lithography and an optical setup for the measurement of continuous diffraction patterns is presented. Sound agreement is found between measurements and simulation, validating both the approach for redirection of light and the fabrication process. The disordered...
Angular dynamics of a small particle in turbulence
Candelier, F; Mehlig, B
2016-01-01
We compute the angular dynamics of a neutrally buoyant nearly spherical particle immersed in an unsteady fluid. We assume that the particle is small, that its translational slip velocity is negligible, and that unsteady and convective inertia are small perturbations. We derive an approximation for the torque on the particle that determines the first inertial corrections to Jeffery's equation. These corrections arise as a consequence of local vortex stretching, and can be substantial in turbulence where local vortex stretching is strong and closely linked to the irreversibility of turbulence.
Full angular analysis of polarized τ → 3 μ decays
Energy Technology Data Exchange (ETDEWEB)
Brueser, Robin; Faller, Sven; Feldmann, Thorsten; Lange, Bjoern O.; Mannel, Thomas [Theoretische Elementarteilchenphysik, Naturwissenschaftlich-technische Fakultaet, Universitaet Siegen, 57068 Siegen (Germany); Turczyk, Sascha [PRISMA Cluster of Excellence and Mainz Institut for Theoretical Physics, Johannes Gutenberg University, 55099 Mainz (Germany)
2015-07-01
The lepton number violating decay τ → 3 μ is extremely suppressed in the Standard Model and its observation would be direct evidence of New Physics. We investigate the decay of polarized τ leptons in a bottom-up approach using dim 6 operators which respect the symmetries of the Standard Model. We show that useful information can be gained from a polarized initial τ, where the external polarization vector allows for a full angular decomposition of the phase space. Partial rates are then analysed to distinguish models with different helicity structures.
New model for holographic storage by simultaneous angular multiplexing
Ibarra, J. C.; Urzua, D.; Olivares-Peréz, A.; Ortiz-Gutierrez, M.
2006-05-01
We describe a technique for holographic storage by simultaneous angular multiplexing to obtain a large-scale holographic memory. We recorded 72 objects at the same time in one point on holographic plate PFG-03M from Slavich Co., using a He-Ne laser (λ = 633 nm). Each object is placed on a circular photographic transparency, separate 0.94 degree each one. The technique allows us simultaneous reconstruction of the 72 images without cross-talk. The diffraction efficiency obtained at order one is 6%. Experimental results are shown.
Area-angular-momentum inequality for axisymmetric black holes.
Dain, Sergio; Reiris, Martin
2011-07-29
We prove the local inequality A≥8π|J|, where A and J are the area and angular momentum of any axially symmetric closed stable minimal surface in an axially symmetric maximal initial data. From this theorem it is proved that the inequality is satisfied for any surface on complete asymptotically flat maximal axisymmetric data. In particular it holds for marginal or event horizons of black holes. Hence, we prove the validity of this inequality for all dynamical (not necessarily near equilibrium) axially symmetric black holes.
Angular Distribution of Photons in Coherent Bremsstrahlung in Deformed Crystals
Parazian, V V
2010-01-01
We investigate the angular distribution of photons in the coherent bremsstrahlung process by high-energy electrons in a periodically deformed single crystal with a complex base. The formula for the corresponding differential cross-section is derived for an arbitrary deformation field. The case is considered in detail when the electron enters into the crystal at small angles with respect to a crystallographic axis. The results of the numerical calculations are presented for SiO2 single crystal and Moliere parameterization of the screened atomic potentials in the case of the deformation field generated by the acoustic wave of S -type.
Photons, phonons, and plasmons with orbital angular momentum in plasmas
Chen, Qiang; Liu, Jian
2016-01-01
Exact eigen modes with orbital angular momentum (OAM) in the complex media of unmagnetized homogeneous plasma are studied. Three exact eigen modes with OAM are discovered, i.e., photons, phonons, and plasmons. It is found that an OAM photon can be excited by two familiar Bessel modes without OAM. For the phonons and plasmons, their OAM are carried by the electrons and ions. The OAM modes in plasmas and their characteristics can be explored for various potential applications in plasma physics and accelerator physics.
Angular distribution of 6He+p elastic scattering
Institute of Scientific and Technical Information of China (English)
LIU Xin; SU Jun; ZENG Sheng; YAN Sheng-Quan; LIAN Gang; HUANG Wu-Zhen; LIU Wei-Ping; WANG You-Bao; LI Zhi-Hong; JIN Sun-Jun; WANG Bao-Xiang; LI Yun-Ju; LI Er-Tao; BAI Xi-Xiang; GUO Bing
2012-01-01
The angular distribution of 1H(6He,p)6He elastic scattering has been measured at Ec.m.=4.3 MeV by using a thick-target inverse kinematic method.The experimental differential cross sections are reproduced by the distorted-wave Born approximation calculation utilizing the CH89 global optical potential parameter set.The real part of CH89 is reduced comparing with other potentials,which may be attributed to the couplings necessary for the weakly bound nuclei.
Measuring the Orbital Angular Momentum of Electron Beams
Guzzinati, Giulio; Béché, Armand; Verbeeck, Jo
2014-01-01
The recent demonstration of electron vortex beams has opened up the new possibility of studying orbital angular momentum (OAM) in the interaction between electron beams and matter. To this aim, methods to analyze the OAM of an electron beam are fundamentally important and a necessary next step. We demonstrate the measurement of electron beam OAM through a variety of techniques. The use of forked holographic masks, diffraction from geometric apertures, diffraction from a knife-edge and the application of an astigmatic lens are all experimentally demonstrated. The viability and limitations of each are discussed with supporting numerical simulations.
ROTATING RINDLER SPACE TIME WITH CONSTANT ANGULAR VELOCITY
Institute of Scientific and Technical Information of China (English)
WANG YONG-CHENG
2000-01-01
A new space time metric is derived from Kerr metric if its mass and location approach to infinite in an appropriate way. The new space-time is an infinitesimal neighborhood nearby one of the two horizon poles of an infinite Kerr black hole. In other words, it is the second order infinitesimal neighborhood nearby one of the two horizon poles of a Kerr black hole. It is fiat and has event horizon and infinite red shift surface. We prove that it is a rotating Rindler space time with constant angular velocity.
Measurements of electron density profiles using an angular filter refractometer
Energy Technology Data Exchange (ETDEWEB)
Haberberger, D., E-mail: dhab@lle.rochester.edu; Ivancic, S.; Hu, S. X.; Boni, R.; Barczys, M.; Craxton, R. S.; Froula, D. H. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14636 (United States)
2014-05-15
A novel diagnostic technique, angular filter refractometry (AFR), has been developed to characterize high-density, long-scale-length plasmas relevant to high-energy-density physics experiments. AFR measures plasma densities up to 10{sup 21} cm{sup −3} with a 263-nm probe laser and is used to study the plasma expansion from CH foil and spherical targets that are irradiated with ∼9 kJ of ultraviolet (351-nm) laser energy in a 2-ns pulse. The data elucidate the temporal evolution of the plasma profile for the CH planar targets and the dependence of the plasma profile on target radius for CH spheres.
Energy and angular momentum sharing in dissipative collisions
Casini, G; Calamai, S; Laforest, R; Maurenzig, P R; Olmi, A; Pasquali, G; Piantelli, S; Poggi, G; Saint-Laurent, F; Steckmeyer, J C; Stefanini, A A; Taccetti, N
2000-01-01
Primary and secondary masses of heavy reaction products have been deduced from kinematics and E-ToF measurements, respectively, for the direct and reverse collisions of 93Nb and 116Sn at 25 AMeV. Light charged particles have also been measured in coincidence with the heavy fragments. Direct experimental evidence of the correlation of energy-sharing with net mass transfer has been found using the information from both the heavy fragments and the light charged particles. The ratio of Hydrogen and Helium multiplicities points to a further correlation of angular momentum sharing with net mass transfer.
Energy and angular momentum sharing in dissipative collisions
Casini, G.; Bini, M.; Calamai, S.; Laforest, R.; Maurenzig, P. R.; Olmi, A.; Pasquali, G.; Piantelli, S.; Poggi, G.; Saint-Laurent, F.; Steckmeyer, J. C.; Stefanini, A. A.; Taccetti, N.
Primary and secondary masses of heavy reaction products have been deduced from kinematics and E-ToF measurements, respectively, for the direct and reverse collisions of 93Nb and 116Sn at 25 AMeV. Light charged particles have also been measured in coincidence with the heavy fragments. Direct experimental evidence of the correlation of energy-sharing with net mass transfer has been found using information from both the heavy fragments and the light charged particles. The ratio of hydrogen and helium multiplicities points to a further correlation of angular momentum sharing with net mass transfer.
Energy and angular momentum sharing in dissipative collisions
Energy Technology Data Exchange (ETDEWEB)
Casini, G.; Bini, M.; Calamai, S.; Maurenzig, P.R.; Olmi, A.; Pasquali, G.; Piantelli, S.; Poggi, G.; Stefanini, A.A.; Taccetti, N. [Istituto Nazionale di Fisica Nucleare, Florence (Italy); Laforest, R.; Steckmeyer, J.C. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire; Saint-Laurent, F. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France)
2000-12-01
Primary and secondary masses of heavy reaction products have been deduced from kinematics and E-ToF measurements, respectively, for the direct and reverse collisions of {sup 93}Nb and {sup 116}Sn at 25 AMeV. Light charged particles have also been measured in coincidence with the heavy fragments. Direct experimental evidence of the correlation of energy-sharing with net mass transfer has been found using information from both the heavy fragments and the light charged particles. The ratio of hydrogen and helium multiplicities points to a further correlation of angular momentum sharing with net mass transfer. (orig.)
Supermode fiber for orbital angular momentum (OAM) transmission.
Li, Shuhui; Wang, Jian
2015-07-13
We present a multi-orbital-angular-momentum (OAM) multi-core supermode fiber (MOMCSF) to transmit OAM modes. The MOMCSF consists of equally-spaced and circularly-arranged multiple cores, in which the core pitch is small enough to support strong coupling OAM supermodes. The characteristics of OAM modes in MOMCSFs with different core pitches and core numbers are analyzed. The performances of mode coupling and nonlinearity are optimized by designing multiple degrees of freedom of the supermode fiber. The obtained results show that the designed MOMCSF can transmit multiple OAM modes with favorable performance of low mode coupling, low nonlinearity, and low modal dependent loss.
Quantum Nuclear Pasta Calculations with Twisted Angular Boundary Conditions
Schuetrumpf, Bastian; Nazarewicz, Witold
2015-10-01
Nuclear pasta, expected to be present in the inner crust of neutron stars and core collapse supernovae, can contain a wide spectrum of different exotic shapes such as nuclear rods and slabs. There are also more complicated, network-like structures, the triply periodic minimal surfaces, already known e.g. in biological systems. These shapes are studied with the Hartree-Fock method using modern Skyrme forces. Furthermore twisted angular boundary conditions are utilized to reduce finite size effects in the rectangular simulation boxes. It is shown, that this improves the accuracy of the calculations drastically and additionally more insights into the mechanism of forming minimal surfaces can be gained.
Energy and Angular Momentum Deposition During Common Envelope Evolution
2003-01-01
Tomo en consideraci on tres procesos que incrementan la tasa de p erdida de masa de la envolvente com un de una gigante de la secuencia principal o de una compa~nera enana blanca que se precipita en espiral dentro de su envolvente. Considero el dep osito de energ a orbital y momento angular orbital en la envolvente de la gigante y la formaci on de \\jets" por la compa~nera acreciente que se propagan dentro de la envolvente. Encuentro que en muchos casos el dep osito del momento an...
Engineering of orbital angular momentum supermodes in coupled optical waveguides
Turpin, A; Polo, J; Mompart, J; Ahufinger, V
2016-01-01
In this work we demonstrate the existence of orbital angular momentum (OAM) bright and dark supermodes in a three-evanescent coupled cylindrical waveguides system. Bright and dark supermodes are characterized by its coupling and decoupling from one of the waveguides, respectively. In addition, we demonstrate that complex couplings between modes of different waveguides appear naturally due to the characteristic spiral phase-front of OAM modes in two-dimensional configurations where the waveguides are arranged forming a triangle. Finally, by adding dissipation to the waveguide uncoupled to the dark supermode, we are able to filter it out, allowing for the design of OAM mode clonners and inverters.
Light beams with orbital angular momentum for free space optics
Institute of Scientific and Technical Information of China (English)
Wu Jing-Zhi; Li Yang-Jun
2007-01-01
The light's orbital angular momentum (OAM) is a consequence of the spiral flow of the electromagnetic energy. In this paper, an analysis of light beams with OAM used for free space optics (FSO) is conducted. The basic description and conception of light's OAM are reviewed. Both encoding information into OAM states of single light beam and encoding information into spatial structure of the mixed optical vortex with OAM are discussed, and feasibility to improve the FSO's performance of security and obstruction of line of sight is examined.
Effect of higher orbital angular momenta in the baryon spectrum
Garcilazo, H; Fernández, F
2001-01-01
We have performed a Faddeev calculation of the baryon spectrum for the chiral constituent quark model including higher orbital angular momentum states. We have found that the effect of these states is important, although a description of the baryon spectrum of the same quality as the one given by including only the lowest-order configurations can be obtained. We have studied the effect of the pseudoscalar quark-quark interaction on the relative position of the positive- and negative-parity excitations of the nucleon as well as the effect of varying the strength of the color-magnetic interaction.
Photons, phonons, and plasmons with orbital angular momentum in plasmas
Chen, Qiang; Qin, Hong; Liu, Jian
2017-01-01
Exact eigen modes with orbital angular momentum (OAM) in the complex media of unmagnetized homogeneous plasmas are studied. Three exact eigen modes with OAM are derived, i.e., photons, phonons, and plasmons. The OAM of different plasma components are closely related to the charge polarities. For photons, the OAM of electrons and ions are of the same magnitude but opposite direction, and the total OAM is carried by the field. For the phonons and plasmons, their OAM are carried by the electrons and ions. The OAM modes in plasmas and their characteristics can be explored for potential applications in plasma physics and accelerator physics. PMID:28164998
Correlation steering in the angularly multimode Raman atomic memory.
Mazelanik, Mateusz; Dąbrowski, Michał; Wasilewski, Wojciech
2016-09-19
We present the possibility of steering the direction of correlations between the off-resonant Raman scattered photons from the angularly multimode atomic memory based on warm rubidium vapors. Using acousto-optic deflectors (AOD) driven by different modulation frequencies, we experimentally change the angle of incidence of the laser beams on the atomic ensemble. By performing correlation measurements for various deflection angles, we verify that we can choose the anti-Stokes light propagation direction independently of the correlated Stokes scattered light in a continuous way. As a result we can select the spatial mode of photons retrieved from the memory, which may be important for future development of quantum information processing.
High-efficiency Autonomous Laser Adaptive Optics
Baranec, Christoph; Law, Nicholas M; Ramaprakash, A N; Tendulkar, Shriharsh; Hogstrom, Kristina; Bui, Khanh; Burse, Mahesh; Chordia, Pravin; Das, Hillol; Dekany, Richard; Kulkarni, Shrinivas; Punnadi, Sujit
2014-01-01
As new large-scale astronomical surveys greatly increase the number of objects targeted and discoveries made, the requirement for efficient follow-up observations is crucial. Adaptive optics imaging, which compensates for the image-blurring effects of Earth's turbulent atmosphere, is essential for these surveys, but the scarcity, complexity and high demand of current systems limits their availability for following up large numbers of targets. To address this need, we have engineered and implemented Robo-AO, a fully autonomous laser adaptive optics and imaging system that routinely images over 200 objects per night with an acuity 10 times sharper at visible wavelengths than typically possible from the ground. By greatly improving the angular resolution, sensitivity, and efficiency of 1-3 m class telescopes, we have eliminated a major obstacle in the follow-up of the discoveries from current and future large astronomical surveys.
HIGH-EFFICIENCY AUTONOMOUS LASER ADAPTIVE OPTICS
Energy Technology Data Exchange (ETDEWEB)
Baranec, Christoph [Institute for Astronomy, University of Hawai' i at Mānoa, Hilo, HI, NZ 96720-2700 (United States); Riddle, Reed; Tendulkar, Shriharsh; Hogstrom, Kristina; Bui, Khanh; Dekany, Richard; Kulkarni, Shrinivas [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Law, Nicholas M. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255 (United States); Ramaprakash, A. N.; Burse, Mahesh; Chordia, Pravin; Das, Hillol; Punnadi, Sujit, E-mail: baranec@hawaii.edu [Inter-University Centre for Astronomy and Astrophysics, Ganeshkhind, Pune 411007 (India)
2014-07-20
As new large-scale astronomical surveys greatly increase the number of objects targeted and discoveries made, the requirement for efficient follow-up observations is crucial. Adaptive optics imaging, which compensates for the image-blurring effects of Earth's turbulent atmosphere, is essential for these surveys, but the scarcity, complexity and high demand of current systems limit their availability for following up large numbers of targets. To address this need, we have engineered and implemented Robo-AO, a fully autonomous laser adaptive optics and imaging system that routinely images over 200 objects per night with an acuity 10 times sharper at visible wavelengths than typically possible from the ground. By greatly improving the angular resolution, sensitivity, and efficiency of 1-3 m class telescopes, we have eliminated a major obstacle in the follow-up of the discoveries from current and future large astronomical surveys.
Content adaptive illumination for Fourier ptychography.
Bian, Liheng; Suo, Jinli; Situ, Guohai; Zheng, Guoan; Chen, Feng; Dai, Qionghai
2014-12-01
Fourier ptychography (FP) is a recently reported technique, for large field-of-view and high-resolution imaging. Specifically, FP captures a set of low-resolution images, under angularly varying illuminations, and stitches them together in the Fourier domain. One of FP's main disadvantages is its long capturing process, due to the requisite large number of incident illumination angles. In this Letter, utilizing the sparsity of natural images in the Fourier domain, we propose a highly efficient method, termed adaptive Fourier ptychography (AFP), which applies content adaptive illumination for FP, to capture the most informative parts of the scene's spatial spectrum. We validate the effectiveness and efficiency of the reported framework, with both simulated and real experiments. Results show that the proposed AFP could shorten the acquisition time of conventional FP, by around 30%-60%.
Adaptively robust filtering with classified adaptive factors
Institute of Scientific and Technical Information of China (English)
CUI Xianqiang; YANG Yuanxi
2006-01-01
The key problems in applying the adaptively robust filtering to navigation are to establish an equivalent weight matrix for the measurements and a suitable adaptive factor for balancing the contributions of the measurements and the predicted state information to the state parameter estimates. In this paper, an adaptively robust filtering with classified adaptive factors was proposed, based on the principles of the adaptively robust filtering and bi-factor robust estimation for correlated observations. According to the constant velocity model of Kalman filtering, the state parameter vector was divided into two groups, namely position and velocity. The estimator of the adaptively robust filtering with classified adaptive factors was derived, and the calculation expressions of the classified adaptive factors were presented. Test results show that the adaptively robust filtering with classified adaptive factors is not only robust in controlling the measurement outliers and the kinematic state disturbing but also reasonable in balancing the contributions of the predicted position and velocity, respectively, and its filtering accuracy is superior to the adaptively robust filter with single adaptive factor based on the discrepancy of the predicted position or the predicted velocity.
Supporting Adaptive and Adaptable Hypermedia Presentation Semantics
Bulterman, D.C.A.; Rutledge, L.; Hardman, L.; Ossenbruggen, J.R. van
1999-01-01
Having the content of a presentation adapt to the needs, resources and prior activities of a user can be an important benefit of electronic documents. While part of this adaptation is related to the encodings of individual data streams, much of the adaptation can/should be guided by the semantics in
Extraordinary Light-Induced Local Angular Momentum near Metallic Nanoparticles.
Alabastri, Alessandro; Yang, Xiao; Manjavacas, Alejandro; Everitt, Henry O; Nordlander, Peter
2016-04-26
The intense local field induced near metallic nanostructures provides strong enhancements for surface-enhanced spectroscopies, a major focus of plasmonics research over the past decade. Here we consider that plasmonic nanoparticles can also induce remarkably large electromagnetic field gradients near their surfaces. Sizeable field gradients can excite dipole-forbidden transitions in nearby atoms or molecules and provide unique spectroscopic fingerprinting for chemical and bimolecular sensing. Specifically, we investigate how the local field gradients near metallic nanostructures depend on geometry, polarization, and wavelength. We introduce the concept of the local angular momentum (LAM) vector as a useful figure of merit for the design of nanostructures that provide large field gradients. This quantity, based on integrated fields rather than field gradients, is particularly well-suited for optimization using numerical grid-based full wave electromagnetic simulations. The LAM vector has a more compact structure than the gradient matrix and can be straightforwardly associated with the angular momentum of the electromagnetic field incident on the plasmonic structures.
Angular momentum transport and evolution of lopsided galaxies
Saha, Kanak
2014-01-01
The surface brightness distribution in the majority of stellar galactic discs falls off exponentially. Often what lies beyond such a stellar disc is the neutral hydrogen gas whose distribution also follows a nearly exponential profile at least for a number of nearby disc galaxies. Both the stars and gas are commonly known to host lopsided asymmetry especially in the outer parts of a galaxy. The role of such asymmetry in the dynamical evolution of a galaxy has not been explored so far. Following Lindblad's original idea of kinematic density waves, we show that the outer part of an exponential disc is ideally suitable for hosting lopsided asymmetry. Further, we compute the transport of angular momentum in the combined stars and gas disc embedded in a dark matter halo. We show that in a pure star and gas disc, there is a transition point where the free precession frequency of a lopsided mode, $\\Omega -\\kappa $, changes from retrograde to prograde and this in turn reverses the direction of angular momentum flow i...
Strong Clustering of Faint Galaxies at Small Angular Scales
Infante, L; Menanteau, F
1996-01-01
The 2-point angular correlation function of galaxies, \\wt, has been computed on equatorial fields observed with the CTIO 4m prime focus, within a total area of 2.31 deg$^2$. In the magnitude range $19\\le m_R \\le 21.5$, corresponding to $\\approx 0.35$, we find an excess of power in \\wt at scales $2''\\le\\theta larger $\\theta$. The significance of this excess is $\\approx 5\\sigma$. At larger scales, $6''< \\theta \\le 24''$, the amplitude of \\wt is 1.6 times smaller than the standard no evolutionary model. At these scales there is remarkable agreement between the present data and Infante \\& Pritchet (1995). At large angular scales ($6''< \\theta \\le 24''$) the data is best described by a model where clustering evolution in $\\xi(r,z)$ has taken place. Strong luminosity evolution cannot be ruled out with the present data. At smaller scales, $2''\\le \\theta \\le 6''$, our data are formally fit by models where $(Ømega=0.2, \\epsilon=0)$. If the mean redshift of our sample is 0.35 then our data show a clear detec...
Statistical Angular Resolution Limit for Ultrawideband MIMO Noise Radar
Directory of Open Access Journals (Sweden)
Xiaoli Zhou
2015-01-01
Full Text Available The two-dimensional angular resolution limit (ARL of elevation and azimuth for MIMO radar with ultrawideband (UWB noise waveforms is investigated using statistical resolution theory. First, the signal model of monostatic UWB MIMO noise radar is established in a 3D reference frame. Then, the statistical angular resolution limits (SARLs of two closely spaced targets are derived using the detection-theoretic and estimation-theoretic approaches, respectively. The detection-theoretic approach is based on the generalized likelihood ratio test (GLRT with given probabilities of false alarm and detection, while the estimation-theoretic approach is based on Smith’s criterion which involves the Cramér-Rao lower bound (CRLB. Furthermore, the relationship between the two approaches is presented, and the factors affecting the SARL, that is, detection parameters, transmit waveforms, array geometry, signal-to-noise ratio (SNR, and parameters of target (i.e., radar cross section (RCS and direction, are analyzed. Compared with the conventional radar resolution theory defined by the ambiguity function, the SARL reflects the practical resolution ability of radar and can provide an optimization criterion for radar system design.
The cosmic web and the orientation of angular momenta
Libeskind, Noam I; Knebe, Alexander; Steinmetz, Matthias; Gottlöber, Stefan; Metuki, Ofer; Yepes, Gustavo
2012-01-01
We use a 64$h^{-1}$Mpc dark matter (DM) only cosmological simulation to examine the large scale orientation of haloes and substructures with respect the cosmic web. A web classification scheme based on the velocity shear tensor is used to assign to each halo in the simulation a web type: knot, filament, sheet or void. Using $\\sim10^6$ haloes that span ~3 orders of magnitude in mass the orientation of the halo's spin and the orbital angular momentum of subhaloes with respect to the eigenvectors of the shear tensor is examined. We find that the orbital angular momentum of subhaloes tends to align with the intermediate eigenvector of the velocity shear tensor for all haloes in knots, filaments and sheets. This result indicates that the kinematics of substructures located deep within the virialized regions of a halo is determined by its infall which in turn is determined by the large scale velocity shear, a surprising result given the virilaized nature of haloes. The non-random nature of subhalo accretion is thus...
Angular dependence of primordial trispectra and CMB spectral distortions
Shiraishi, Maresuke; Liguori, Michele
2016-01-01
Under the presence of anisotropic sources in the inflationary era, the trispectrum of the primordial curvature perturbation is sensitive to the angles between each wave vector. We examine the imprints left by curvature trispectra, in which the angular dependence is described by Legendre polynomials, on the $TT\\mu$ bispectrum, generated by the correlation between temperature anisotropies (T) and chemical potential spectral distortions ($\\mu$) of the Cosmic Microwave Background (CMB). Due to the angular dependence of the primordial signal, the corresponding $TT\\mu$ bispectrum strongly differs in shape from $TT\\mu$ sourced by the usual $g_{\\rm NL}$ or $\\tau_{\\rm NL}$ local trispectra, enabling us to obtain an unbiased estimation. From a Fisher matrix analysis, we find that, in a cosmic-variance-limited (CVL) survey of $TT\\mu$, a minimum detectable value of the quadrupolar Legendre coefficient is $d_2 \\sim 0.01$, which is 4 orders of magnitude better than the best value attainable from the $TTTT$ CMB trispectrum....
Angular Resolution of the LISA Gravitational Wave Detector
Cutler, C
1998-01-01
We calculate the angular resolution of the planned LISA detector, a space-based laser interferometer for measuring low-frequency gravitational waves from galactic and extragalactic sources. LISA is not a pointed instrument; it is an all-sky monitor with a quadrupolar beam pattern. LISA will measure simultaneously both polarization components of incoming gravitational waves, so the data will consist of two time series. All physical properties of the source, including its position, must be extracted from these time series. LISA's angular resolution is therefore not a fixed quantity, but rather depends on the type of signal and on how much other information must be extracted. Information about the source position will be encoded in the measured signal in three ways: 1) through the relative amplitudes and phases of the two polarization components, 2) through the periodic Doppler shift imposed on the signal by the detector's motion around the Sun, and 3) through the further modulation of the signal caused by the d...
Angular momentum of disc galaxies with a lognormal density distribution
Marr, John Herbert
2015-01-01
Whilst most galaxy properties scale with galaxy mass, similar scaling relations for angular momentum are harder to demonstrate. A lognormal (LN) density distribution for disc mass provides a good overall fit to the observational data for disc rotation curves for a wide variety of galaxy types and luminosities. In this paper, the total angular momentum J and energy $\\vert{}$E$\\vert{}$ were computed for 38 disc galaxies from the published rotation curves and plotted against the derived disc masses, with best fit slopes of 1.683$\\pm{}$0.018 and 1.643$\\pm{}$0.038 respectively, using a theoretical model with a LN density profile. The derived mean disc spin parameter was $\\lambda{}$=0.423$\\pm{}$0.014. Using the rotation curve parameters V$_{max}$ and R$_{max}$ as surrogates for the virial velocity and radius, the virial mass estimator $M_{disc}\\propto{}R_{max}V_{max}^2$ was also generated, with a log-log slope of 1.024$\\pm{}$0.014 for the 38 galaxies, and a proportionality constant ${\\lambda{}}^*=1.47\\pm{}0.20\\time...
Cluster Multi-spacecraft Determination of AKR Angular Beaming
Mutel, R L; Pickett, J S
2008-01-01
Simultaneous observations of AKR emission using the four-spacecraft Cluster array were used to make the first direct measurements of the angular beaming patterns of individual bursts. By comparing the spacecraft locations and AKR burst locations, the angular beaming pattern was found to be narrowly confined to a plane containing the magnetic field vector at the source and tangent to a circle of constant latitude. Most rays paths are confined within 15 deg of this tangent plane, consistent with numerical simulations of AKR k-vector orientation at maximum growth rate. The emission is also strongly directed upward in the tangent plane, which we interpret as refraction of the rays as they leave the auroral cavity. The narrow beaming pattern implies that an observer located above the polar cap can detect AKR emission only from a small fraction of the auroral oval at a given location. This has important consequences for interpreting AKR visibility at a given location. It also helps re-interpret previously published...
Wave mediated angular momentum transport in astrophysical boundary layers
Hertfelder, Marius
2015-01-01
Context. Disk accretion onto weakly magnetized stars leads to the formation of a boundary layer (BL) where the gas loses its excess kinetic energy and settles onto the star. There are still many open questions concerning the BL, for instance the transport of angular momentum (AM) or the vertical structure. Aims. It is the aim of this work to investigate the AM transport in the BL where the magneto-rotational instability (MRI) is not operating owing to the increasing angular velocity $\\Omega(r)$ with radius. We will therefore search for an appropriate mechanism and examine its efficiency and implications. Methods. We perform 2D numerical hydrodynamical simulations in a cylindrical coordinate system $(r, \\varphi)$ for a thin, vertically inte- grated accretion disk around a young star. We employ a realistic equation of state and include both cooling from the disk surfaces and radiation transport in radial and azimuthal direction. The viscosity in the disk is treated by the {\\alpha}-model; in the BL there is no v...
ELECTRON ANGULAR DISTRIBUTIONS IN DISSOCIATIVE PHOTOIONIZATION OF THE HYDROGEN MOLECULE.
Directory of Open Access Journals (Sweden)
Jhon F. Pérez-Torres
2009-06-01
Full Text Available Se propone un método para calcular distribuciones angulares de electrones ionizados en la molécula de hidrógeno fija en el espacio sometida a pulsos láser intensos y ultracortos, basado en la solución desde primeros principios de la ecuación de Schrödinger dependiente del tiempo. Esta solución nos permite tener una visión temporal de la interferencias generadas en el canal de ionización disociativa (en el espectro de energía cinética de los protones debido a la presencia de la autoionización de estados doblemente excitados de la molécula de hidrógeno. Se muestra específicamente cómo la autoionización durante el proceso de fotoionización disociativa también puede inducir una asimetría en la distribución angular del electrón ionizado con respecto a la inversión nuclear, un efecto no intuitivo a pesar de estar tratando con un sistema homonuclear.
Neutron angular distribution in plutonium-240 spontaneous fission
Marcath, Matthew J.; Shin, Tony H.; Clarke, Shaun D.; Peerani, Paolo; Pozzi, Sara A.
2016-09-01
Nuclear safeguards applications require accurate fission models that exhibit prompt neutron anisotropy. In the laboratory reference frame, an anisotropic neutron angular distribution is observed because prompt fission neutrons carry momentum from fully accelerated fission fragments. A liquid organic scintillation detector array was used with pulse shape discrimination techniques to produce neutron-neutron cross-correlation time distributions and angular distributions from spontaneous fission in a 252Cf, a 0.84 g 240Pueff metal, and a 1.63 g 240Pueff metal sample. The effect of cross-talk, estimated with MCNPX-PoliMi simulations, is removed from neutron-neutron coincidences as a function of the angle between detector pairs. Fewer coincidences were observed at detector angles near 90°, relative to higher and lower detector angles. As light output threshold increases, the observed anisotropy increases due to spectral effects arising from fission fragment momentum transfer to emitted neutrons. Stronger anisotropy was observed in Cf-252 spontaneous fission prompt neutrons than in Pu-240 neutrons.
Cosmological Tests Using the Angular Size of Galaxy Clusters
Wei, Jun-Jie; Melia, Fulvio
2014-01-01
We use measurements of the galaxy-cluster angular size versus redshift to test and compare the standard model (LCDM) and the R_h=ct Universe. We show that the latter fits the data with a reduced chi^2_dof=0.786 for a Hubble constant H_0= 72.6 (-3.4+3.8) km/s/Mpc, and H_0 is the sole parameter in this model. By comparison, the optimal flat LCDM model, with two free parameters (including Omega_m=0.50 and H_0=73.9 (-9.5+10.6) km/s/Mpc), fits the angular-size data with a reduced chi^2_dof=0.806. On the basis of their chi^2_dof values alone, both models appear to account for the data very well in spite of the fact that the R_h=ct Universe expands at a constant rate, while LCDM does not. However, because of the different number of free parameters in these models, selection tools, such as the Bayes Information Criterion, favour R_h=ct over LCDM with a likelihood of ~86% versus ~14%. These results impact the question of galaxy growth at large redshifts. Previous work suggested an inconsistency with the underlying cos...
Measuring angular diameter distances of strong gravitational lenses
Jee, Inh; Suyu, Sherry H
2014-01-01
The distance-redshift relation plays a fundamental role in constraining cosmological models. In this paper, we show that measurements of positions and time delays of strongly lensed images of a background galaxy, as well as those of the velocity dispersion and mass profile of a lens galaxy, can be combined to extract the angular diameter distance of the lens galaxy. Physically, as the velocity dispersion and the time delay give a gravitational potential ($GM/r$) and a mass ($GM$) of the lens, respectively, dividing them gives a physical size ($r$) of the lens. Comparing the physical size with the image positions of a lensed galaxy gives the angular diameter distance to the lens. A mismatch between the exact locations at which these measurements are made can be corrected by measuring a local slope of the mass profile. We expand on the original idea put forward by Paraficz and Hjorth, who analyzed singular isothermal lenses, by allowing for an arbitrary slope of a power-law spherical mass density profile, an ex...
Squeezing of X waves with orbital angular momentum
Ornigotti, Marco; Villari, Leone Di Mauro; Szameit, Alexander; Conti, Claudio
2017-01-01
Multilevel quantum protocols may potentially supersede standard quantum optical polarization-encoded protocols in terms of amount of information transmission and security. However, for free-space telecommunications, we do not have tools for limiting loss due to diffraction and perturbations, as, for example, turbulence in air. Here we study propagation invariant quantum X waves with angular momentum; this representation expresses the electromagnetic field as a quantum gas of weakly interacting bosons. The resulting spatiotemporal quantized light pulses are not subject to diffraction and dispersion, and are intrinsically resilient to disturbances in propagation. We show that spontaneous down-conversion generates squeezed X waves useful for quantum protocols. Surprisingly, the orbital angular momentum affects the squeezing angle, and we predict the existence of a characteristic axicon aperture for maximal squeezing. These results may boost the applications in free space of quantum optical transmission and multilevel quantum protocols, and may also be relevant for novel kinds of interferometers, such as satellite-based gravitational wave detectors.
Three-dimensional angular domain optical projection tomography
Ng, Eldon; Vasefi, Fartash; Roumeliotis, Michael; Kaminska, Bozena; Carson, Jeffrey J. L.
2011-03-01
Angular Domain Imaging (ADI) has been previously demonstrated to generate projection images of attenuating targets embedded within a turbid medium. The imaging system employs a silicon micro-tunnel array positioned between the sample and the detection system to reject scattered photons that have deviated from the initial propagation direction and to select for ballistic and quasi-ballistic photons that have retained their forward trajectory. Two dimensional tomographic images can be reconstructed from ADI projections collected at a multitude of angles. The objective of this work was to extend the system to three dimensions by collecting several tomographic images and stacking the reconstructed slices to generate a three dimensional volume representative of the imaging target. A diode laser (808nm, CW) with a beam expander was used to illuminate the sample cuvette. An Angular Filter Array (AFA) of 80 μm × 80 μm square-shaped tunnels 2 cm in length was used to select for image forming quasi-ballistic photons. Images were detected with a linear CCD. Our approach was to use a SCARA robot to rotate and translate the sample to collect sufficient projections to reconstruct a three dimensional volume. A custom designed 3D target consisting of 4 truncated cones was imaged and reconstructed with filtered backprojection and iterative methods. A 0.5 mm graphite rod was used to collect the forward model, while a truncated pseudoinverse was used to approximate the backward model for the iterative algorithm.
Recovering 3D clustering information with angular correlations
Asorey, Jacobo; Gaztanaga, Enrique; Lewis, Antony
2012-01-01
We study how to recover the full 3D clustering information of P(\\vec{k},z), including redshift space distortions (RSD), from 2D tomography using the angular auto and cross spectra of different redshift bins C_\\ell(z,z'). We focus on quasilinear scales where the minimum scale \\lambda_{min} or corresponding maximum wavenumber k_{max}= 2\\pi/\\lambda_{min} is targeted to be between k_{max}={0.05-0.2} h/Mpc. For spectroscopic surveys, we find that we can recover the full 3D clustering information when the redshift bin width \\Delta z used in the 2D tomography is similar to the targeted minimum scale, i.e. \\Delta z ~ {0.6-0.8} \\lambda_{min} H(z)/c which corresponds to \\Delta z ~ 0.01-0.05 for z\\Delta z and most radial information is intrinsically lost. The remaining information can be recovered from the 2D tomography if we use \\Delta z ~ 2\\sigma_z. While 3D and 2D analysis are shown here to be equivalent, the advantage of using angular positions and redshifts is that we do not need a fiducial cosmology to convert to ...
Exploring the orbital angular momentum of betatron radiation
Martins, Joana; Hehmann, Guenda; Fonseca, Ricardo; Silva, Luis; Vieira, Jorge
2016-10-01
Betatron radiation from laser-wakefield accelerators (LWFA) can be used as a broadband X-ray source. Betatron x-rays have attracted great interest and have applications in biological imaging which have been demonstrated experimentally (see for instance). Endowing betatron radiation with well defined states of orbital angular momentum (OAM), a fundamental property of light by which its wave fronts become twisted, could further enhance the imaging spatial resolution. However, the conditions for the generation of betatron x-rays with OAM, and the fundamental mechanisms underlying the transfer of OAM from electron trajectories to the radiation they emit, remain outstanding open questions. To explore these exciting open challenges, we investigate the OAM spectral content of betatron x-rays in LWFA. We explore the conditions and laser driver characteristics (with/without orbital and spin angular momentum) that can enable the emission of OAM x-rays. We support our studies by 3D numerical modelling, using the particle-in-cell code Osiris and using the post processing radiation code jRad. also at DCTI/ISCTE Instituto Universitario de Lisboa, Lisboa, Portugal.
Angular distribution in the neutron-induced fission of actinides
Directory of Open Access Journals (Sweden)
Leong L.S.
2013-12-01
Full Text Available Above 1 MeV of incident neutron energy the fission fragment angular distribution (FFAD has generally a strong anisotropic behavior due to the combination of the incident orbital momentum and the intrinsic spin of the fissioning nucleus. This effect has to be taken into account for the efficiency estimation of devices used for fission cross section measurements. In addition it bears information on the spin deposition mechanism and on the structure of transitional states. We designed and constructed a detection device, based on Parallel Plate Avalanche Counters (PPAC, for measuring the fission fragment angular distributions of several isotopes, in particular 232Th. The measurement has been performed at n_TOF at CERN taking advantage of the very broad energy spectrum of the neutron beam. Fission events were recognized by back to back detection in coincidence in two position-sensitive detectors surrounding the targets. The detection efficiency, depending mostly on the stopping of fission fragments in backings and electrodes, has been computed with a Geant4 simulation and validated by the comparison to the measured case of 235U below 3 keV where the emission is isotropic. In the case of 232Th, the result is in good agreement with previous data below 10 MeV, with a good reproduction of the structures associated to vibrational states and the opening of second chance fission. In the 14 MeV region our data are much more accurate than previous ones which are broadly scattered.
Ion angular distribution simulation of the HEMP Thruster
Duras, Julia; Koch, Norbert; Kahnfeld, Daniel; Bandelow, Gunnar; Matthias, Paul; Lüskow, Karl Felix; Schneider, Ralf; Kemnitz, Stefan
2016-10-01
Ion angular current and energy distributions are important parameters for ion thrusters, which are typically measured at a few tens of centimetres to a few meters distance from thruster exit. However, fully kinetic Particle-in-Cell simulations are not able to simulate such domain sizes, due to high computational costs. Therefore, a parallelisation strategy of the code is presented to reduce computational time. To map diagnostics information from the domain boundary of the calculational domain to the positions of experimental diagnostics the concept of transfer functions is introduced. The calculated ion beam angular distributions in the plume region are quite sensitive to boundary conditions of the potential, possible additional source contributions, e.g. from secondary electron emission at vessel walls, and charge exchange collisions. This work was supported by the Bavarian State Ministry of Education Science and the Arts and the German Space Agency DLR. We also like to thank R. Heidemann from THALES Electron Devices GmbH, for interesting and stimulating discussions.
Neutron angular distribution in plutonium-240 spontaneous fission
Energy Technology Data Exchange (ETDEWEB)
Marcath, Matthew J., E-mail: mmarcath@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States); Shin, Tony H.; Clarke, Shaun D. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States); Peerani, Paolo [European Commission at the Joint Research Centre, Ispra (Italy); Pozzi, Sara A. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States)
2016-09-11
Nuclear safeguards applications require accurate fission models that exhibit prompt neutron anisotropy. In the laboratory reference frame, an anisotropic neutron angular distribution is observed because prompt fission neutrons carry momentum from fully accelerated fission fragments. A liquid organic scintillation detector array was used with pulse shape discrimination techniques to produce neutron-neutron cross-correlation time distributions and angular distributions from spontaneous fission in a {sup 252}Cf, a 0.84 g {sup 240}Pu{sub eff} metal, and a 1.63 g {sup 240}Pu{sub eff} metal sample. The effect of cross-talk, estimated with MCNPX-PoliMi simulations, is removed from neutron-neutron coincidences as a function of the angle between detector pairs. Fewer coincidences were observed at detector angles near 90°, relative to higher and lower detector angles. As light output threshold increases, the observed anisotropy increases due to spectral effects arising from fission fragment momentum transfer to emitted neutrons. Stronger anisotropy was observed in Cf-252 spontaneous fission prompt neutrons than in Pu-240 neutrons. - Highlights: • Pu-240 prompt fission fast-neutron anisotropy was quantified for the first time. • MCNPX-PoliMi and MPPost codes were used to remove cross-talk neutron detections from experiment results. • Cf-252 spontaneous fission neutrons were found to be more anisotropic than Pu-240 neutrons.
Angular spreading measurements using MeV ion microscopes
Energy Technology Data Exchange (ETDEWEB)
Whitlow, Harry J., E-mail: harry.whitlow@he-arc.ch [Institut des Microtechnologies Appliquées, Haute Ecole Arc Ingénierie, Eplatures-Gris 17, CH-2300 La Chaux-de-Fonds (Switzerland); Department of Physics, P.O. Box 35 (YFL), FI-40014 University of Jyväskylä (Finland); Ren, Minqin; Chen, Xiao; Osipowicz, Thomas; Kan, Jeroen A. van; Watt, Frank [Centre for Ion Beam Applications, National University of Singapore (Singapore)
2013-07-01
The sharpness of MeV ion microscope images is governed by small-angle scattering and associated lateral spreading of the ion beam in the sample. We have investigated measurement of the half-angle of the angular spreading distribution by characterising the image blurring in direct-Scanning Transmission Ion Microscopy (direct-STIM). In these tests Mylar™ foils of 0.5–6 μm were used to induce angular spreading. Images were taken of an electron microscope grid using 2 MeV protons with, and without, the foils in the beam path. The blurring was measured by fitting the width of a circular Gaussian point spread function to the images with and without the foil in position. The results show the half-angle width of the spreading has a square root dependence on foil thickness that lies intermediate between SRIM predictions and the theoretical estimates (Bird and Williams fits to the Sigmund and Winterbon data and Amsel et al.)
Bilateral angular carpal deformity in a dog with craniomandibular osteopathy.
Pettitt, R; Fox, R; Comerford, E J; Newitt, A
2012-01-01
A four-month-old West Highland White Terrier was presented to the Small Animal Teaching Hospital at the University of Liverpool with the complaint of a bilateral angular carpal deformity. A 20° valgus deformity was present in both thoracic limbs, centred on the distal radial physes. Both distal ulnas were grossly thickened and there was concomitant thickening of the rostral mandible and calvarium. The dog exhibited signs of resentment on palpation of the mandible and signs of pain were elicited on flexion and extension of both elbow joints. No signs of pain were evident on palpation of the ulnas or calvarium. Radiographic images of both ulnas showed marked amorphous periosteal new bone formation. The distal ulnar physes were closed centrally and both elbow joints had humeroulnar subluxation. Radiographic changes to the calvarium and mandibular rami were consistent with a diagnosis of craniomandibular osteopathy. A bilateral ulna ostectomy was performed to correct the angular limb deformity and elbow subluxations. Histology of the ostectomised pieces showed changes consistent with craniomandibular osteopathy.
Orbit classification of low and high angular momentum stars
Zotos, Euaggelos E
2014-01-01
We determine the character of orbits of stars moving in the meridional plane $(R,z)$ of an axially symmetric time-independent disk galaxy model with a spherical central nucleus. In particular, we try to reveal the influence of the value of the angular momentum on the different families of orbits of stars, by monitoring how the percentage of chaotic orbits, as well as the percentages of orbits of the main regular resonant families evolve when angular momentum varies. The smaller alignment index (SALI) was computed by numerically integrating the equations of motion as well as the variational equations to extensive samples of orbits in order to distinguish safely between ordered and chaotic motion. In addition, a method based on the concept of spectral dynamics that utilizes the Fourier transform of the time series of each coordinate is used to identify the various families of regular orbits and also to recognize the secondary resonances that bifurcate from them. Our investigation takes place both in the physica...
Asymptotic Diffusion-Limit Accuracy of Sn Angular Differencing Schemes
Energy Technology Data Exchange (ETDEWEB)
Bailey, T S; Morel, J E; Chang, J H
2009-11-05
In a previous paper, Morel and Montry used a Galerkin-based diffusion analysis to define a particular weighted diamond angular discretization for S{sub n}n calculations in curvilinear geometries. The weighting factors were chosen to ensure that the Galerkin diffusion approximation was preserved, which eliminated the discrete-ordinates flux dip. It was also shown that the step and diamond angular differencing schemes, which both suffer from the flux dip, do not preserve the diffusion approximation in the Galerkin sense. In this paper we re-derive the Morel and Montry weighted diamond scheme using a formal asymptotic diffusion-limit analysis. The asymptotic analysis yields more information than the Galerkin analysis and demonstrates that the step and diamond schemes do in fact formally preserve the diffusion limit to leading order, while the Morel and Montry weighted diamond scheme preserves it to first order, which is required for full consistency in this limit. Nonetheless, the fact that the step and diamond differencing schemes preserve the diffusion limit to leading order suggests that the flux dip should disappear as the diffusion limit is approached for these schemes. Computational results are presented that confirm this conjecture. We further conjecture that preserving the Galerkin diffusion approximation is equivalent to preserving the asymptotic diffusion limit to first order.
Robust adaptive control of underwater vehicles: A comparative study
Directory of Open Access Journals (Sweden)
Thor I. Fossen
1996-01-01
Full Text Available Robust adaptive control of underwater vehicles in 6 DOF is analysed in the context of measurement noise. The performance of the adaptive control laws of Sadegh and Harowitz (1990 and Slotine and Benedetto (1990 are compared. Both these schemes require that all states are measured, that is the velocities and positions in surge, sway, heave, roll, pitch and yaw. However, for underwater vehicles it is difficult to measure the linear velocities whereas angular velocity measurements can be obtained by using a 3 axes angular rate sensor. This problem is addressed by designing a nonlinear observer for linear velocity state estimation. The proposed observer requires that the position and the attitude are measured, e.g. by using a hydroacoustic positioning system for linear positions, two gyros for roll and pitch and a compass for yaw. In addition angular rate measurements will be assumed available from a 3-axes rate sensor or a state estimator. It is also assumed that the measurement rate is limited to 2 Hz for all the sensors. Simulation studies with a 3 DOF AUV model are used to demonstrate the convergence and robustness of the adaptive control laws and the velocity state observer.
Personalized Adaptive Learning
Kravcik, Milos; Specht, Marcus; Naeve, Ambjorn
2009-01-01
Kravcik, M., Specht, M., & Naeve, A. (2008). Personalized Adaptive Learning. Presentation of PROLEARN WP1 Personalized Adaptive Learning at the final review meeting. February, 27, 2008, Hannover, Germany.
Is angular momentum in the horizontal plane during gait a controlled variable?
Thielemans, Valerie; Meyns, Pieter; Bruijn, Sjoerd M
2014-04-01
It has been suggested that angular momentum in the horizontal plane during human gait is controlled (i.e., kept minimal). However, this has not been explored in conditions when angular momentum of different segments is manipulated explicitly. In order to examine the behavior of angular momentum, 12 participants walked in 17 conditions in which angular momentum of either the arms or legs was manipulated. Subjects walked at different step lengths, different speeds and with an additional weight on either the wrist or ankle. Angular momentum of total body, arms and legs was calculated from gait kinematics. Increasing step length increased total body and leg angular momentum. When weight was added to the limbs, arm and leg angular momentum were affected and counteracted each other, so that total body angular momentum did not change. Moreover, increasing walking speed increased arm, leg and total body angular momentum. Thus, it may be concluded that if angular momentum is controlled (which only seems to be the case for conditions when weights are added), it is not strictly controlled in all gait conditions (as it may increase by walking faster/with larger steps).
LENUS (Irish Health Repository)
Creane, Arthur
2012-07-01
Many soft biological tissues contain collagen fibres, which act as major load bearing constituents. The orientation and the dispersion of these fibres influence the macroscopic mechanical properties of the tissue and are therefore of importance in several areas of research including constitutive model development, tissue engineering and mechanobiology. Qualitative comparisons between these fibre architectures can be made using vector plots of mean orientations and contour plots of fibre dispersion but quantitative comparison cannot be achieved using these methods. We propose a \\'remodelling metric\\' between two angular fibre distributions, which represents the mean rotational effort required to transform one into the other. It is an adaptation of the earth mover\\'s distance, a similarity measure between two histograms\\/signatures used in image analysis, which represents the minimal cost of transforming one distribution into the other by moving distribution mass around. In this paper, its utility is demonstrated by considering the change in fibre architecture during a period of plaque growth in finite element models of the carotid bifurcation. The fibre architecture is predicted using a strain-based remodelling algorithm. We investigate the remodelling metric\\'s potential as a clinical indicator of plaque vulnerability by comparing results between symptomatic and asymptomatic carotid bifurcations. Fibre remodelling was found to occur at regions of plaque burden. As plaque thickness increased, so did the remodelling metric. A measure of the total predicted fibre remodelling during plaque growth, TRM, was found to be higher in the symptomatic group than in the asymptomatic group. Furthermore, a measure of the total fibre remodelling per plaque size, TRM\\/TPB, was found to be significantly higher in the symptomatic vessels. The remodelling metric may prove to be a useful tool in other soft tissues and engineered scaffolds where fibre adaptation is also present.
Angular and axial deformities of the legs of children.
McDonough, M W
1984-12-01
Age is often a determining factor in establishing a treatment program for these axial and angular problems. As can be seen, the deformities of torsion are noticeable from early life. Any tibial torsion should be treated early, but an excessive medial range of motion in the infant leg with a corresponding adequate lateral range of motion of the limb may be cautiously observed. Medial femoral torsion is a normal early finding in the infant thigh. The problem becomes evident as the child matures without the corresponding reduction in femoral torsion, leading to a persistence of fetal or infantile alignment. The gait consequences are usually noticed at 4 to 8 years of age. The angular changes generally are a delayed finding noticed in stance. The bowleg may be associated with marked tibial torsion and picked up early but the Blount's patient has been traditionally definable at 2 years of age. Levin and Drennan may hasten the time of diagnosis with their radiographic criteria. Knock-knee is an alignment disturbance noticed during the early to mid-childhood years, age 4 to 8 years. The diagnosis is important, differentiating physiologic from torsion-related deformities, and treatment, if warranted, should not be delayed. Generally the earlier these problems are discovered, the more optimistic the prognosis. Since the pediatric limb is in a constant state of transition, there will be a perpetual argument as to the need or efficacy of various approaches to the problems of knock-knee and bowleg. If observation is the treatment of choice, the percentage of cases which go on to osteotomies and epiphyseal stapling will continue. For those with axial or angular deformities, degenerative arthritis of the knee may be forthcoming. Swanson, Greene, and Allis warned of problems becoming "unphysiologic." If we consider the epiphyseal malleability, not only to deformity but to correction, we can appreciate Lenoir's comment of "every day the problem goes untreated is a golden
A new unity for angular measurements in strabismus
Directory of Open Access Journals (Sweden)
Harley E. A. Bicas
2014-10-01
Full Text Available The practical advantages of quantifying an angle by a ratio of linear lengths instead of arcs of circles has led to the definition of the prism-diopter, a conventional unity for numbering prisms and measuring strabismic deviations. However, a major inconvenience of using prism-diopter unities to express angular measurements is the non-linearity of the scale, which reaches an infinite value for the angle of 90º, then becomes negative, with decreasing magnitudes for increasing angles between 90º and 180º. As a consequence, arithmetical operations and comparisons of angles measured by such unities present errors of very great magnitudes. In order to retain the advantages of defining an angle by straight line dimensions but to diminish the severe inconveniences of this method, a new definition of the prism-diopter is proposed. Here, instead of defining the prism-diopter by the asymmetrical condition, the conception of this new unity is based on a geometrically symmetrical condition; that of the relationship of an isosceles triangle (where the leg is perpendicular to the bisector of the angle and the bisector itself . The condition of symmetry for the definition of the new unity represents a conceptual advance because it reproduces the already well accepted, conventional criteria for quantifying the value of a prism, that of its minimum deviation. Furthermore, it corresponds to the most commonly observed clinical conditions of binocular balance. The absolute differences between the unitary values of the prism-diopter and that of the new unity are negligible (0.0025%, but the scale of values expressed by the new unity is closer to the ideal scale of angular measurements. (With the new unity, the infinite value is only reached for an angle of 180º and the errors due to arithmetical operations are much smaller. Numerical examples showing the advantages of using the new unity of angular measurements instead of the prism-diopter are presented. A
A new unity for angular measurements in strabismus.
Bicas, Harley E A
2014-10-01
The practical advantages of quantifying an angle by a ratio of linear lengths instead of arcs of circles has led to the definition of the prism-diopter, a conventional unity for numbering prisms and measuring strabismic deviations. However, a major inconvenience of using prism-diopter unities to express angular measurements is the non-linearity of the scale, which reaches an infinite value for the angle of 90º, then becomes negative, with decreasing magnitudes for increasing angles between 90º and 180º. As a consequence, arithmetical operations and comparisons of angles measured by such unities present errors of very great magnitudes. In order to retain the advantages of defining an angle by straight line dimensions but to diminish the severe inconveniences of this method, a new definition of the prism-diopter is proposed. Here, instead of defining the prism-diopter by the asymmetrical condition, the conception of this new unity is based on a geometrically symmetrical condition; that of the relationship of an isosceles triangle (where the leg is perpendicular to the bisector of the angle and the bisector itself ). The condition of symmetry for the definition of the new unity represents a conceptual advance because it reproduces the already well accepted, conventional criteria for quantifying the value of a prism, that of its minimum deviation. Furthermore, it corresponds to the most commonly observed clinical conditions of binocular balance. The absolute differences between the unitary values of the prism-diopter and that of the new unity are negligible (0.0025%), but the scale of values expressed by the new unity is closer to the ideal scale of angular measurements. (With the new unity, the infinite value is only reached for an angle of 180º and the errors due to arithmetical operations are much smaller.) Numerical examples showing the advantages of using the new unity of angular measurements instead of the prism-diopter are presented. A mathematical
Spatio-angularly multiplexed (SAM) holographic storage in photorefractive crystals
Tao, Shiquan
In this thesis a novel multiplexing scheme for dense holographic storage in photorefractive crystals, Spatio-Angular Multiplexing (or SAM), is described in detail. In SAM Fourier transform holograms are formed in spatially overlapping regions of a crystal and are distinguished from one another by using variously angled reference beams. SAM takes advantage of both the high storage density possible using angularly multiplexed volume holograms and also the low crosstalk possible using spatially multiplexed Fourier transform holograms. Compared to pure spatial multiplexing, SAM increases the storage capacity by fully utilising the volume of the storage medium. On the other hand, SAM reduces the number of holograms overlapping any one hologram in a given volume, and so increases the diffraction efficiency achievable as compared to pure angular multiplexing. SAM offers the possibility of incorporating the recorded crystal into a content addressable memory (CAM) system for parallel access of all stored patterns. In order to obtain the maximum diffraction efficiency and signal to noise ratio, the hologram must be replayed by a readout beam incident at the correct angle of readout beam. The optimum angle may be shifted away from the angle used in recording by a ''Bragg-shift", caused (under certain conditions) by phase coupling between the two writing beams during recording. Although this Bragg shift is small, a large diffraction efficiency enhancement is obtained when the grating is read out at the optimum angle. We have calculated the Bragg shift, using a numerical calculation based on an earlier theory, and have obtained good agreement with experiment. Using the novel SAM scheme, we have succeeded in storing 756 high resolution binary patterns in an Fe:LiNbO3 crystal of volume 1cm3, with an average diffraction efficiency of 0.5%. This large database is designed for practical use in a novel associative memory system, called a high order feedback neural network (HOFNET
Angular Spacing Control for Segmented Data Pages in Angle-Multiplexed Holographic Memory
Kinoshita, Nobuhiro; Muroi, Tetsuhiko; Ishii, Norihiko; Kamijo, Koji; Kikuchi, Hiroshi; Shimidzu, Naoki; Ando, Toshio; Masaki, Kazuyoshi; Shimizu, Takehiro
2011-09-01
To improve the recording density of angle-multiplexed holographic memory, it is effective to increase the numerical aperture of the lens and to shorten the wavelength of the laser source as well as to increase the multiplexing number. The angular selectivity of a hologram, which determines the multiplexing number, is dependent on the incident angle of not only the reference beam but also the signal beam to the holographic recording medium. The actual signal beam, which is a convergent or divergent beam, is regarded as the sum of plane waves that have different propagation directions, angular selectivities, and optimal angular spacings. In this paper, focusing on the differences in the optimal angular spacing, we proposed a method to control the angular spacing for each segmented data page. We investigated the angular selectivity of a hologram and crosstalk for segmented data pages using numerical simulation. The experimental results showed a practical bit-error rate on the order of 10-3.
The photonic wheel: demonstration of a state of light with purely transverse angular momentum
Banzer, Peter; Aiello, Andrea; Marquardt, Christoph; Lindlein, Norbert; Bauer, Thomas; Leuchs, Gerd
2012-01-01
The concept of angular momentum is ubiquitous to many areas of physics. In classical mechanics, a system may possess an angular momentum which can be either transverse (e.g., in a spinning wheel) or longitudinal (e.g., for a fluidic vortex) to the direction of motion. Photons, however, are well-known to exhibit intrinsic angular momentum which is longitudinal only: the spin angular momentum defining the beam polarization and the orbital angular momentum associated with a spiraling phase front. Here we show that it is possible to generate a novel state of light that contains purely transverse angular momentum, the analogue of a spinning mechanical wheel. We use an optical nano-probing technique to experimentally demonstrate its occurrence in our setup. Such a state of light can provide additional rotational degree of freedom in optical tweezers and optical manipulation.
Effects of angular range on image quality of chest digital tomosynthesis
Lee, Haenghwa; Kim, Ye-seul; Choi, Sunghoon; Lee, Dong-Hoon; Choi, Seungyeon; Kim, Hee-Joung
2016-03-01
Chest digital tomosynthesis (CDT) is a new 3D imaging technique that can be expected to improve clinical diagnosis over conventional chest radiography. We investigated the effect of the angular range of data acquisition on the image quality using newly developed CDT system. The four different acquisition sets were studied using +/-15°, +/-20°, +/-30°, and +/-35° angular ranges with 21 projection views (PVs). The point spread function (PSF), modulation transfer function (MTF), artifact spread function (ASF), and normalized contrast-to-noise ratio (CNR) were used to evaluate the image quality. We found that increasing angular ranges improved vertical resolution. The results indicated that there was the opposite relationship of the CNR with angular range for the two tissue types. While CNR for heart tissue increased with increasing angular range, CNR for spine bone decreased. The results showed that the angular range is an important parameter for the CDT exam.
Numerical Solution of the Evolution Equation for Orbital Angular Momentum of Partons in the Nucleon
Martin, O; Schäfer, A
1999-01-01
The evolution of orbital angular momentum distributions within the radiative parton model is studied. We use different scenarios for the helicity weighted parton distributions and consider a broad range of input distributions for orbital angular momentum. In all cases we are lead to the conclusion that the absolute value of the average angular momentum per parton peaks at relatively large $x\\approx 0.1$ for perturbatively accessible scales. Furthermore, in all scenarios considered here the average orbital angular momentum per parton is several times larger for gluons than for quarks which favours gluon initiated reactions to measure orbital angular momentum. The large gluon polarization typically obtained in NLO-fits to DIS data is primarily canceled by the gluon orbital angular momentum.
Conservation of the spin and orbital angular momenta in electromagnetism
Bliokh, Konstantin Y; Nori, Franco
2014-01-01
We review and re-examine the description and separation of the spin and orbital angular momenta (AM) of an electromagnetic field in free space. While the spin and orbital AM of light are not separately-meaningful physical quantities in orthodox quantum mechanics or classical field theory, these quantities are routinely measured and used for applications in optics. A meaningful quantum description of the spin and orbital AM of light was recently provided by several authors, which describes separately conserved and measurable integral values of these quantities. However, the electromagnetic field theory still lacks corresponding locally-conserved spin and orbital AM currents. In this paper, we construct these missing local spin and orbital AM densities and fluxes that satisfy the proper continuity equations. We show that these are physically measurable and conserved quantities. These are, however, not Lorentz-covariant, so only make sense in the single laboratory reference frame of the measurement probe. The fl...
Observation of Four-Photon Orbital Angular Momentum Entanglement
Hiesmayr, B. C.; de Dood, M. J. A.; Löffler, W.
2016-02-01
We demonstrate genuine multipartite quantum entanglement of four photons in their orbital angular momentum degrees of freedom, where a high-dimensional discrete Hilbert space is attached to each photon. This can encode more quantum information compared to the qubit case, but it is a long-standing problem to entangle more than two such photons. In our experiment we use pulsed spontaneous parametric down-conversion to produce the photon quadruplets, which allows us to detect about one four-photon event per second. By means of quantum state reconstruction and a suitable witness operator we find that the photon quadruplets form a genuine multipartite entangled symmetric Dicke state. This opens a new tool for addressing foundational questions in quantum mechanics, and for exploration of novel high-dimensional multiparty quantum information applications such as secret sharing.
Creating High-Harmonic Beams with Controlled Orbital Angular Momentum
Boyd, Robert W.
A beam of light with an angle-dependent phase Φ = lϕ , where ϕ is the azimuthal coordinate, about the beam axis carries an orbital angular momentum (OAM) of lℏ per photon. Such beams have been exploited to provide superresolution in visible-light microscopy. The ability to create extreme ultraviolet or soft-x-ray beams with controllable OAM would be a critical step towards extending superresolution methods to extremely small feature size. Here we show that OAM is conserved during the process of high-harmonic generation (HHG). Experimentally, we use a fundamental beam with l = 1 and interferometrically determine that the q-th harmonic has an OAM quantum number l equal to its harmonic order q. We also show theoretically how to couple an arbitrary low value of the OAM quantum number l to any harmonic order q in a controlled manner. Our results open a route to microscopy on the molecular, or even submolecular, scale.
Angularly Deformed Special Relativity and its Results for Quantum Mechanics
Glinka, Lukasz Andrzej
2015-01-01
In this paper, the deformed Special Relativity, which leads to an essentially new theoretical context of quantum mechanics, is presented. The formulation of the theory arises from a straightforward analogy with the Special Relativity, but its foundations are laid through the hypothesis on breakdown of the velocity-momentum parallelism which affects onto the Einstein equivalence principle between mass and energy of a relativistic particle. Furthermore, the derivation is based on the technique of an eikonal equation whose well-confirmed physical role lays the foundations of both optics and quantum mechanics. As a result, we receive the angular deformation of Special Relativity which clearly depicts the new deformation-based theoretical foundations of physics, and, moreover, offers both constructive and consistent phenomenological discussion of the theoretical issues such like imaginary mass and formal superluminal motion predicted in Special Relativity for this case. In the context of the relativistic theory, p...
Angular dependence models for radiance to flux conversion
Green, Richard N.; Suttles, John T.; Wielicki, Bruce A.
1990-01-01
Angular dependence models (ADM) used for converting the measured radiance to flux at the top of the atmosphere are reviewed, and emphasis is placed on the measure of their effectiveness and the implications of requiring the ADMs to satisfy reciprocity. The overall significance of the ADMs is figured out by analyzing the same satellite data with a single Lambertian model, single mean model, and the 12 Earth Radiation Budget Experiment (ERBE) ADMs. It is shown that the Lambertian ADM is inadequate, while the mean ADM results in nearly unbiased fluxes but creates substantial differences for individual pixel fluxes. The standard ERBE ADM works well except for a 10-pct to 15-pct albedo growth across the scan; a modified ADM based on the standard ERBE ADM but forced to satisfy the principle of reciprocity increases the limb brightening and reduces the albedo growth but does not improve the scanner and nonscanner intercomparison.
Nondestructive Measurement of Orbital Angular Momentum for an Electron Beam
Larocque, Hugo; Bouchard, Frédéric; Grillo, Vincenzo; Sit, Alicia; Frabboni, Stefano; Dunin-Borkowski, Rafal E.; Padgett, Miles J.; Boyd, Robert W.; Karimi, Ebrahim
2016-10-01
Free electrons with a helical phase front, referred to as "twisted" electrons, possess an orbital angular momentum (OAM) and, hence, a quantized magnetic dipole moment along their propagation direction. This intrinsic magnetic moment can be used to probe material properties. Twisted electrons thus have numerous potential applications in materials science. Measuring this quantity often relies on a series of projective measurements that subsequently change the OAM carried by the electrons. In this Letter, we propose a nondestructive way of measuring an electron beam's OAM through the interaction of this associated magnetic dipole with a conductive loop. Such an interaction results in the generation of induced currents within the loop, which are found to be directly proportional to the electron's OAM value. Moreover, the electron experiences no OAM variations and only minimal energy losses upon the measurement, and, hence, the nondestructive nature of the proposed technique.
Capacity of arbitrary-order orbital angular momentum multiplexing system
Zhao, Yaqin; Zhong, Xin; Ren, Guanghui; He, Shengyang; Wu, Zhilu
2017-03-01
Arbitrary-order orbital angular momentum multiplexing (AOAMM) systems utilize OAM modes with both integer and fractional topological charges which are non-orthogonal. In this paper, the transmission matrix and the capacity per unit bandwidth, i.e., the spectral efficiency (SE) of an AOAMM system is derived based on the spatial cross correlations of the OAM submodes under different aperture conditions. The results show that in limited apertures, the SEs of AOAMM systems increase dramatically as the interval of two adjacent OAM submodes decreases by losing orthogonality. AOAMM systems are effective choices for satisfying the explosive growth of the communication requirements. This paper provides insight into the selection of spatially multiplexing approaches and the design of interference mitigation techniques for AOAMM systems with increased SEs.
Accessing the quark orbital angular momentum with Wigner distributions
Cedric, Lorce
2012-01-01
The quark orbital angular momentum (OAM) has been recognized as an important piece of the proton spin puzzle. A lot of effort has been invested in trying to extract it quantitatively from the generalized parton distributions (GPDs) and the transverse-momentum dependent parton distributions (TMDs), which are accessed in high-energy processes and provide three-dimensional pictures of the nucleon. Recently, we have shown that it is more natural to access the quark OAM from the phase-space or Wigner distributions. We discuss the concept of Wigner distributions in the context of quantum field theory and show how they are related to the GPDs and the TMDs. We summarize the different definitions discussed in the literature for the quark OAM and show how they can in principle be extracted from the Wigner distributions.
Attitude angular measurement system based on MEMS accelerometer
Luo, Lei
2014-09-01
For the purpose of monitoring the attitude of aircraft, an angular measurement system using a MEMS heat convection accelerometer is presented in this study. A double layers conditioning circuit that center around the single chip processor is designed and built. Professional display software with the RS232 standard is used to communicate between the sensor and the computer. Calibration experiments were carried out to characterize the measuring system with the range of - 90°to +90°. The curves keep good linearity with the practical angle. The maximum deviation occurs at the 90°where the value is 2.8°.The maximum error is 1.6% and the repeatability is measured to be 2.1%. Experiments proved that the developed measurement system is capable of measuring attitude angle.
Angular distributions of very low energy recoil ions
Energy Technology Data Exchange (ETDEWEB)
Gonzalez Lepera, C.E.; Breinig, M.; Burgdoerfer, J.; DeSerio, R.; Elston, S.B.; Gibbons, J.P.; Huelskoetter, H.P.; Liljeby, L.; Vane, C.R.; Sellin, I.A.
1986-01-01
We present the first measurements of the angular distribution of recoil ions near 90/sup 0/ with respect to the incident projectile direction. Beams of 22.5 and 33 MeV chlorine ions (incident charge states q =4,5,8) have been used as ''hammer'' beams incident on Ne atoms. We confirm the long standing assumption that these recoil ions are ejected preferentially at angles near 90/sup 0/ with respect to the primary beam direction and with energies typically less than 5 eV. Recoil ions ejected around 90/sup 0/ have an energy distribution appreciably wider than those ejected at either larger or smaller angles. 9 refs., 6 figs.
Squeezing of X waves with orbital angular momentum
Ornigotti, Marco; Szameit, Alexander; Conti, Claudio
2016-01-01
Multi-level quantum protocols may potentially supersede standard quantum optical polarization-encoded protocols in terms of amount of information transmission and security. However, for free space telecomunications, we do not have tools for limiting loss due to diffraction and perturbations, as for example turbulence in air. Here we study propagation invariant quantum X-waves with angular momentum; this representation expresses the electromagnetic field as a quantum gas of weakly interacting bosons. The resulting spatio-temporal quantized light pulses are not subject to diffraction and dispersion, and are intrinsically resilient to disturbances in propagation. We show that spontaneous down-conversion generates squeezed X-waves useful for quantum protocols. Surprisingly the orbital angural momentum affects the squeezing angle, and we predict the existence of a characteristic axicon aperture for maximal squeezing. There results may boost the applications in free space of quantum optical transmission and multi-l...
Angular solar absorptance of absorbers used in solar thermal collectors.
Tesfamichael, T; Wäckelgård, E
1999-07-01
The optical characterization of solar absorbers for thermal solar collectors is usually performed by measurement of the spectral reflectance at near-normal angle of incidence and calculation of the solar absorptance from the measured reflectance. The solar absorptance is, however, a function of the angle of incidence of the light impinging on the absorber. The total reflectance of two types of commercial solar-selective absorbers, nickel-pigmented anodized aluminum, and sputtered nickel nickel oxide coated aluminum are measured at angles of incidence from 5 to 80 in the wavelength range 300-2500 nm by use of an integrating sphere. From these measurements the angular integrated solar absorptance is determined. Experimental data are compared with theoretical calculations, and it is found that optical thin-film interference effects can explain the significant difference in solar absorptance at higher angles for the two types of absorbers.
On the Angular Width of Diffractive Beam in Anisotropic Media
Lock, Edwin H
2011-01-01
2-D diffraction patterns arising in the far-field region were investigated theoretically for the case, when the plane wave with non collinear group and phase velocities is incident on the wide slit in opaque screen with arbitrary orientation. This investigation was carried out by consideration as an example of magnetostatic surface wave diffraction in tangentially magnetized ferrite slab. It was deduced the universal analytical formula, which one can use to calculate the angular width of diffractive beam in any 2-D anisotropic geometries for the waves of various nature. It was shown, that in 2-D anisotropic geometries this width may be not only more or less then the value L/D (L - wavelength of incident wave, D - length of slit), but it also may be equal to zero in certain conditions.
Visualization of scattering angular distributions with the SAP code
Fernandez, J. E.; Scot, V.; Basile, S.
2010-07-01
SAP (Scattering Angular distribution Plot) is a graphical tool developed at the University of Bologna to compute and plot Rayleigh and Compton differential cross-sections (atomic and electronic), form-factors (FFs) and incoherent scattering functions (SFs) for single elements, compounds and mixture of compounds, for monochromatic excitation in the range of 1-1000 keV. The computation of FFs and SFs may be performed in two ways: (a) by interpolating Hubbell's data from EPDL97 library and (b) by using semi-empirical formulas as described in the text. Two kinds of normalization permit to compare the plots of different magnitudes, by imposing a similar scale. The characteristics of the code SAP are illustrated with one example.
Tighter spots of light with superposed orbital angular momentum beams
Woźniak, Paweł; Bouchard, Frédéric; Karimi, Ebrahim; Leuchs, Gerd; Boyd, Robert W
2016-01-01
The possibility of focusing light to an ever tighter spot has important implications for many applications and fields of optics research, such as nano-optics and plasmonics, laser-scanning microscopy, optical data storage and many more. The size of lateral features of the field at the focus depends on several parameters, including the numerical aperture of the focusing system, but also the wavelength and polarization, phase and intensity distribution of the input beam. Here, we study the smallest achievable focal feature sizes of coherent superpositions of two co-propagating beams carrying opposite orbital angular momentum. We investigate the feature sizes for this class of beams not only in the scalar limit, but also use a fully vectorial treatment to discuss the case of tight focusing. Both our numerical simulations and our experimental results confirm that lateral feature sizes considerably smaller than those of a tightly focused Gaussian light beam can be observed. These findings may pave the way for impr...
Encoding Orbital Angular Momentum of Lights in Magnets
Fujita, Hiroyuki
2016-01-01
Breaking the diffraction limit and focusing laser beams to nanometre-scale are becoming possible with the help of recent developments in plasmonics. This allows us to explore nano-scale physics induced by laser beams with complex spatial profiles like optical vortex, or laser carrying orbital angular momentum (OAM). On the basis of numerical calculations using Landau-Lifshitz-Gilbert equation, here we propose two OAM-dependent phenomena induced by optical vortex, spin waves with multipolar and spiral wave fronts, and ultrafast generation of various kinds of topological defects in chiral magnets. We show that by using Tera Hz optical vortex, we can generate skyrmionic defects with timescale orders of magnitude shorter than by other known schemes.
Symmetries in the angular distribution of exclusive semileptonic B decays
Egede, Ulrik; Matias, Joaquim; Ramon, Marc; Reece, Will
2010-01-01
We discuss a method to construct observables protected against QCD uncertainties based on the angular distribution of the exclusive Bd -> K(*0}(-> Kpi) l+ l- decay. We focus on the identification and the interpretation of all the symmetries of the distribution. They constitute a key ingredient to construct a set of so-called transverse observables. We work in the framework of QCD factorization at NLO supplemented by an estimate of power-suppressed Lambda/mb corrections. A discussion of the new physics properties of two of the transverse asymmetries, AT^{(2)} and AT^{(5)}, is presented. A comparison between the transverse asymmetry AT^{(2)} and the forward-backward asymmetry shows that AT^{(2)} emerges as an improved version of it.
Texture in equal-channel angular pressed aluminum and nickel
Energy Technology Data Exchange (ETDEWEB)
Vogel, S.C.; Beyerlein, I.J.; Bourke, M.A.M.; Tome, C.N.; Rangaswamy, P. [Los Alamos National Lab., Los Alamos, NM (United States); Xu, C.; Langdon, T.G. [Univ. of Southern California, Los Angeles, CA (United States)
2002-07-01
Nano-structured metals with advantageous mechanical properties can be produced using severe plastic deformation techniques such as equal channel angular pressing (ECAP). Metals and alloys processed by ECAP have much higher yield strengths than the equivalent unprocessed material while retaining high ductilities, an extremely attractive combination of properties. Implicit in the process are the introduction of repetitive shear strains of 100% which introduce texture, the modeling of which is challenging. In this work, we present results from a neutron diffraction study on aluminum and nickel samples processed by ECAP. The results are compared to predictions from a visco-plastic self-consistent (VPSC) model. By taking into account grain-grain interactions in the model the agreement between the predicted and measured orientation distributions is improved. The results show also that the initial texture affects the texture evolution, at least up to strains of the order of {proportional_to}1, i.e. one ECAP pass. (orig.)
Angular dependence of the coercivity in arrays of ferromagnetic nanowires
Energy Technology Data Exchange (ETDEWEB)
Holanda, J. [Departamento de Física, Universidade Federal de Pernambuco, Recife 50670-901, PE (Brazil); Silva, D.B.O. [Pós-Graduação em Ciência de Materiais, Universidade Federal de Pernambuco, Recife 50670-901, PE (Brazil); Padrón-Hernández, E., E-mail: padron@df.ufpe.br [Departamento de Física, Universidade Federal de Pernambuco, Recife 50670-901, PE (Brazil); Pós-Graduação em Ciência de Materiais, Universidade Federal de Pernambuco, Recife 50670-901, PE (Brazil)
2015-03-15
We present a new magnetic model for polycrystalline nanowires arrays in porous anodic aluminum oxide. The principal consideration here is the crystalline structure and the morphology of the wires and them the dipolar interactions between the crystals into the wire. Other aspect here is the direct calculation of the dipolar energy for the interaction of one wire with the others in the array. The free energy density was formulated for polycrystalline nanowires arrays in order to determinate the anisotropy effective field. It was using the microstructure study by scanning and transmission electron microscopy for the estimation of the real structure of the wires. After the structural analysis we used the angular dependences for the coercivity field and for the remnant magnetization to determine the properties of the wires. All analysis were made by the theory treatment proposed by Stoner and Wohlfarth.
Weak measurements with orbital-angular-momentum pointer states.
Puentes, G; Hermosa, N; Torres, J P
2012-07-27
Weak measurements are a unique tool for accessing information about weakly interacting quantum systems with minimal back action. Joint weak measurements of single-particle operators with pointer states characterized by a two-dimensional Gaussian distribution can provide, in turn, key information about quantum correlations that can be relevant for quantum information applications. Here we demonstrate that by employing two-dimensional pointer states endowed with orbital angular momentum (OAM), it is possible to extract weak values of the higher order moments of single-particle operators, an inaccessible quantity with Gaussian pointer states only. We provide a specific example that illustrates the advantages of our method both in terms of signal enhancement and information retrieval.
Chip-Scale Continuously Tunable Optical Orbital Angular Momentum Generator
Sun, Jie; Moresco, Michele; Coolbaugh, Douglas; Watts, Michael R
2014-01-01
Light carrying orbital angular momentum (OAM) has potential to impact a wide variety of applications ranging from optical communications to quantum information and optical forces for the excitation and manipulation of atoms, molecules, and micro-particles. The unique advantage of utilizing OAM in these applications relies, to a large extent, on the use of multiple different OAM states. Therefore, it is desirable to have a device that is able to gen- erate light with freely adjustable OAM states in an integrated form for large- scale integration. We propose and demonstrate a compact silicon photonic integrated circuit to generate a free-space optical beam with OAM state con- tinuously tuned from a single electrical input signal, realizing both integer and non-integer OAM states. The compactness and flexibility of the device and its compatibility with complementary metal-oxide-semiconductor (CMOS) pro- cessing hold promise for integration with other silicon photonic components for wide-ranging applications.
Energy and angular distributions of atmospheric muons at the Earth
Shukla, Prashant
2016-01-01
A fair knowledge of the atmospheric muon distributions at Earth is a prerequisite for the simulations of cosmic ray setups and rare event search detectors. A modified power law is proposed for atmospheric muon energy distribution which gives good description of the cosmic muon data in low as well as high energy regime. Using this distribution, analytical forms for zenith angle ($\\theta$) distribution are obtained. Assuming a flat Earth, it leads to the $\\cos^{n-1}\\theta$ form where it is shown that the parameter $n$ is nothing but the power of the energy distribution. A new analytical form for zenith angle distribution is obtained without assuming a flat Earth which gives an improved description of the data at all angles even above $70^o$. These distributions are tested with the available atmospheric muon data of energy and angular distributions. The parameters of these distributions can be used to characterize the cosmic muon data as a function of energy, angle and altitude.
Detection of orbital angular momentum using a photonic integrated circuit.
Rui, Guanghao; Gu, Bing; Cui, Yiping; Zhan, Qiwen
2016-06-20
Orbital angular momentum (OAM) state of photons offer an attractive additional degree of freedom that has found a variety of applications. Measurement of OAM state, which is a critical task of these applications, demands photonic integrated devices for improved fidelity, miniaturization, and reconfiguration. Here we report the design of a silicon-integrated OAM receiver that is capable of detecting distinct and variable OAM states. Furthermore, the reconfiguration capability of the detector is achieved by applying voltage to the GeSe film to form gratings with alternate states. The resonant wavelength for arbitrary OAM state is demonstrated to be tunable in a quasi-linear manner through adjusting the duty cycle of the gratings. This work provides a viable approach for the realization of a compact integrated OAM detection device with enhanced functionality that may find important applications in optical communications and information processing with OAM states.
Energy, momentum and angular momentum conservations in de Sitter gravity
Lu, Jia-An
2016-08-01
In de Sitter (dS) gravity, where gravity is a gauge field introduced to realize the local dS invariance of the matter field, two kinds of conservation laws are derived. The first kind is a differential equation for a dS-covariant current, which unites the canonical energy-momentum (EM) and angular momentum (AM) tensors. The second kind presents a dS-invariant current which is conserved in the sense that its torsion-free divergence vanishes. The dS-invariant current unites the total (matter plus gravity) EM and AM currents. It is well known that the AM current contains an inherent part, called the spin current. Here it is shown that the EM tensor also contains an inherent part, which might be observed by its contribution to the deviation of the dust particle’s world line from a geodesic. All the results are compared to the ordinary Lorentz gravity.
Rapid generation of light beams carrying orbital angular momentum.
Mirhosseini, Mohammad; Magaña-Loaiza, Omar S; Chen, Changchen; Rodenburg, Brandon; Malik, Mehul; Boyd, Robert W
2013-12-16
We report a technique for encoding both amplitude and phase variations onto a laser beam using a single digital micro-mirror device (DMD). Using this technique, we generate Laguerre-Gaussian and vortex orbital-angular-momentum (OAM) modes, along with modes in a set that is mutually unbiased with respect to the OAM basis. Additionally, we have demonstrated rapid switching among the generated modes at a speed of 4 kHz, which is much faster than the speed regularly achieved by phase-only spatial light modulators (SLMs). The dynamic control of both phase and amplitude of a laser beam is an enabling technology for classical communication and quantum key distribution (QKD) systems that employ spatial mode encoding.
Catenary optics for achromatic generation of perfect optical angular momentum.
Pu, Mingbo; Li, Xiong; Ma, Xiaoliang; Wang, Yanqin; Zhao, Zeyu; Wang, Changtao; Hu, Chenggang; Gao, Ping; Huang, Cheng; Ren, Haoran; Li, Xiangping; Qin, Fei; Yang, Jing; Gu, Min; Hong, Minghui; Luo, Xiangang
2015-10-01
The catenary is the curve that a free-hanging chain assumes under its own weight, and thought to be a "true mathematical and mechanical form" in architecture by Robert Hooke in the 1670s, with nevertheless no significant phenomena observed in optics. We show that the optical catenary can serve as a unique building block of metasurfaces to produce continuous and linear phase shift covering [0, 2π], a mission that is extremely difficult if not impossible for state-of-the-art technology. Via catenary arrays, planar optical devices are designed and experimentally characterized to generate various kinds of beams carrying orbital angular momentum (OAM). These devices can operate in an ultra-broadband spectrum because the anisotropic modes associated with the spin-orbit interaction are almost independent of the incident light frequency. By combining the optical and topological characteristics, our approach would allow the complete control of photons within a single nanometric layer.
Radial and angular-momentum Regge trajectories: a systematic approach
Directory of Open Access Journals (Sweden)
Arriola E.R.
2012-12-01
Full Text Available We present the analysis of Ref. [1] of the radial (n and angular-momentum (J Regge trajectories for all light-quark meson states listed in the Particle Data Tables. The parameters of the trajectories are obtained with linear regression, with weight of each resonance inversely proportional to its half-width squared, (Γ/22. The joint analysis in the (n, J, M2 Regge plane indicates, at the 4.5 standard deviation level, that the slopes in n are larger from the slopes in J. Thus no strict universality of slopes occurs in the light non-strange meson sector. We also extend our analysis to the kaon sector.
Be star outbursts: transport of angular momentum by waves
Neiner, C; Saio, H; Lee, U
2013-01-01
The Be phenomenon, that is the ejection of matter from Be stars into a circumstellar disk, has been a long lasting mystery. In the last few years, the CoRoT (Convection, Rotation and planetary Transits) satellite brought clear evidence that Be outbursts are directly correlated with pulsations. We found that it may be the transport of angular momentum by waves or pulsation modes that brings the already rapid stellar rotation to its critical value at the surface, and allows the star to eject material. The recent discovery of stochastically excited gravito-inertial modes by CoRoT in a hot Be star strengthens this scenario. We present the CoRoT observations and modeling of several Be stars and describe the new picture of the Be phenomenon which arose from these results.
Be Star Outbursts: Transport of Angular Momentum by Waves
Neiner, C.; Mathis, S.; Saio, H.; Lee, U.
2013-12-01
The Be phenomenon, that is the ejection of matter from Be stars into a circumstellar disk, has been a long lasting mystery. In the last few years, the CoRoT (Convection Rotation and planetary Transits) satellite brought clear evidence that Be outbursts are directly correlated with pulsations. We found that it may be the transport of angular momentum by waves or pulsation modes that brings the already rapid stellar rotation to its critical value at the surface, and allows the star to eject material. The recent discovery of stochastically excited gravito-inertial modes by CoRoT in a hot Be star strengthens this scenario. We present the CoRoT observations and modeling of several Be stars and describe the new picture of the Be phenomenon which arose from these results.
High angular resolution diffusion imaging with stimulated echoes
DEFF Research Database (Denmark)
Lundell, Henrik; Alexander, Daniel C; Dyrby, Tim B
2014-01-01
other than the diffusion gradients in the STEAM sequence contribute much greater diffusion weighting than in PGSE and lead to a disrupted experimental design. Here, we introduce a simple compensation to the STEAM acquisition that avoids the orientational bias and disrupted experiment design...... that these gradient pulses can otherwise produce. The compensation is simple to implement by adjusting the gradient vectors in the diffusion pulses of the STEAM sequence, so that the net effective gradient vector including contributions from diffusion and other gradient pulses is as the experiment intends. High...... angular resolution diffusion imaging (HARDI) data were acquired with and without the proposed compensation. The data were processed to derive standard diffusion tensor imaging (DTI) maps, which highlight the need for the compensation. Ignoring the other gradient pulses, a bias in DTI parameters from STEAM...